Tag: human evolution

The evolution of laughter

June 5, 2009 • 8:55 am

Laughter appears to be a “human universal”: one of those many traits that Donald Brown, in his book Human Universals, found in every society.  Well, does that mean it is a trait that evolved in our ancestors, or did it merely appear as a cultural phenomenon early in human society, and spread to all other societies?  One bit of evidence is that children who are deaf and blind, and thus can’t see or hear other people laughing, still laugh.  This suggests (but of course does not prove) that it is an innate, genetically coded trait, though it says nothing about whether it might have been an adaptive trait.

New research just reported in Current Biology by Davila Ross et al. (see here for a short BBC summary of the work; be sure to click on the video to see a gorilla “laughing”!) suggests that laughter is at least an evolved phenomenon, for our relatives appear to show similar vocalizations when tickled, and our closer relatives show more similar vocalizations.

Davila Ross et al. tickled 3 human infants, 7 orangutas, 5 gorillas, 4 chimpanzees, 5 bonobos (pygmy chimps) and 1 siamang, recording their vocalizations. (What a great job!)  Acoustic analysis of the vocalizations produced a phylogeny, or “family tree” of their similarities.  Strikingly, the family tree based on “tickle-vocalization” analysis is congruent with the known phylogeny based on DNA analysis:

laffs

Importantly,  the authors note that several features of human laughter, like its rapid “ha ha ha” type of vocalization, and its expression only during “egressive airflow” (science-ese for “breathing out”) are found in our relatives as well.

So laughter, at least when being tickled, appears to be an evolved, innate phenomenon.  As I emphasized above, this says nothing about whether it was selected for directly, whether it was a byproduct of something else that was selected, or is simply a nonadaptive epiphenomenon.  But as I write, evolutionary psychologists are working on why evolution may have promoted laughter.  Stay tuned.

Did cooking make us human?

May 30, 2009 • 2:06 pm

Well, everybody’s looking for what propelled us from our common ancestor with chimps to the wonderful species we are today. If it’s not genes, it’s culture.  Today’s NYT discusses Richard Wrangham’s new theory (previously mentioned on this website) about how the taming of fire and its use to cook food were crucial events in making our species what it is today.  I am skeptical (I’ve seen many of these theories come and go), but still looking forward to reading Wrangham’s. new book, Catching Fire: How Cooking Made us Human.

A gene for human speech?

May 30, 2009 • 8:16 am

In yesterday’s New York Times, Nicholas Wade reports new research on the FOXP2 gene (see original Cell paper by Enard et al. here).   If you’ve read WEIT, you’ll remember that I discuss FOXP2 as one of those potential genes that “makes us human.”  In other words, evolutionary change at this gene was supposed to have been involved in one of the key traits — speech –that distinguish us from other primates.   This supposition is based on some genetic and developmental observations:

1.  When mutated, FOXP2 causes both speech and speech comprehension difficulties in humans,

2.  The gene has evolved very quickly on the “human” side of our lineage since we split from the chimp lineage (and very slowly among mammals in general), leading researchers to suppose that natural selection for its effect on speech caused the rapid evolution, and

3.  When FOXP2 is mutated in mice, the young mouse pups have trouble making ultrasonic squeaks (a way of communicating with their mother). These squeaks were taken to be homologous with human speech.

However, I’ve been pretty cautious about considering FOXP2 a “human-ness” gene, for there is a lot of wishful thinking in this are.  We (and especially journalists!) are just so eager to find those genes that differentiate us from our “lower” relatives.  The new paper describes research designed to address this question.

What Enard et al. did was to change the sequence of the FOXP2 gene in mice so that it produced a protein having the same two amino acids that differentiate chimps from humans (there is also one amino acid difference between mice and chimps, so the “human” gene in mice actually was not exactly identical to the real human gene).  They then looked at the behavior, brains, and bodies of mice who had two copies of the “human” allele compared to mice having their own “mouse” allele.   The major effects of this genetic engineering were the following:

1.  The human gene reduced the “exploratory behavior” of mice,

2. The human gene increased the length of brain dendrites (inter-nerve-cell connections) in mice compared to those in carriers of the “mouse” allele, and

3.  Mice “pups” with the human gene produced ultrasonic “squeak calls” that had a significantly lower frequency (i.e., vibrations per second) than those produced by mice with the normal mouse allele.

From this the authors conclude that this transgenic experiment sheds light on the evolution of speech and language in humans.  It’s this conclusion (and the transgenic manipulation itself, which is the first time that an evolutionary hypothesis has been studied by changing a mouse protein to a human protein) that gave the authors such publicity, and got their work promoted in the Times.   But, as in the case of the darwinius primate fossil, I think the results are overblown.

All the authors have shown is that putting the human copy of a gene into a mouse changes the structure of the mouse brain and changes the squeaks of babies (what about the adult squeaks, by the way? Why weren’t they studied?).  While this is consistent with a role of FOXP2 in the evolution of human speech, it’s not very impressive.  FOXP2 is active in many tissues, and these effects could be merely pathologies.

Of course the definitive experiment, swapping a human or chimp gene with the copy from the other species, and observing the result, is unethical.

At any rate, I don’t think we’re much closer to finding “humanness” genes than we were before.  Indeed, there may be many, many genes that differentiate us from chimps (see WEIT for an estimate); and if the effet of each gene is very small, we won’t readily find those elusive “humanness”” genes.

The lesson is caveat emptor, at least when it comes to reading about science in the newspapers.

__________________________

Enard et al. (2009).  A humanized version of FOXP2 affects cortico-basal ganglia circuits in mice.  Cell 137:961-971.

Darwinius: what’s at issue?

May 21, 2009 • 3:10 pm

by Greg Mayer

I’m leaving in a few days for Costa Rica, and Jerry is back, so this will be my last post on Darwinius, at least for awhile. At least three different issues have been debated in the blogosphere concerning “Ida“: 1) What are her phylogenetic relationships; 2) Was the media campaign excessive; and 3) Has the name been published?

Darwinius on toast1) What are her phylogenetic relationships? This is the most important one, because it is, as John Maynard Smith once put it, about the world, and not about names. Is Darwinius close to the common ancestor of monkeys, apes, and men, or is it a member of the group that includes lemurs and lorises? The question has been raised and discussed most forcefully by Brian Switek at Laelaps, who thinks the evidence presented for relationship to monkeys and apes is weak. To my mind (and I’m not a specialist in primates or even mammals), he’s got a strong point, and we can look forward to a publication by Brian (or some other critic) on this issue.

2) Was the media campaign excessive? The short answer is yes. I expressed some uneasiness over the media campaign here at WEIT, and many others have documented the extravagant claims and consequent media misunderstandings further. See especially what Carl Zimmer had at the Loom, Brian at Laelaps, and PZ Myers at Pharyngula. But by far the best (or at least funniest) take on this was Ed Yong’s satirical evisceration of the inflated media campaign at Not Exactly Rocket Science, from which I have been kindly permitted to reproduce the by now iconic “Darwinius on Toast” above. There are many unresolved questions concerning how to present science to the public, and differing views concerning how aggressive a media campaign should be, but this one was at least one step beyond.

3) Has the name been published? This is the most technical issue, and is about names (rather than the world), but it’s attracted the most attention. See the posts here at WEIT, the Loom (and here), the Lancelet, and Laelaps, including the ensuing commentary by, among others, Henry Gee, Martin Brazeau, and Larry Witmer. There are several issues, and I’ll treat them very briefly (since this is a blog post, and not a paper in the Bulletin of Zoological Nomenclature!).  For reference, The International Code is online here.

3a) Has the name Darwinius masillae been published (in the sense of the Code) in Plosone? No. Many people have noted that Art. 8.6 requires non-paper works to be deposited in 5 major libraries, and that a statement to this effect must be included in the paper. No such statement is in the paper. More importantly, although it has been noted in only one comment I’ve seen, Art. 9 goes on to specify that nothing distributed by the web counts as being published. The non-paper works envisioned in Art. 8 are things like CDs, not web postings. So, the various remedies proposed, such as reposting on Plosone with the requisite statement, would not work. To be published, a non-Web work must be made: paper, CD, DVD (the latter two requiring the fulfillment of the 5 major libraries rule), or something else which satisfies Arts. 8 and 9.

3ai) Can the name be made available by publishing a short paper (on paper) with a bibliographic reference to the Plosone posting? No, because availability by bibliographic reference must be by reference to a published work (Art. 13.1.2), and anything on the Web is not published (Art. 9.8).

3b) Has the name been published elsewhere? I hope not, but fear it may have been. I pointed out that the various newspaper articles may count as publication, because they meet the various criteria for publication (obtainability, simultaneity, etc.; Art. 8), and also contain 1) the name, and 2) are “accompanied by a description or definition that states in words characters that are purported to differentiate the taxon” (Art. 13.11), and even follow Recommendation 13A: “a summary of the characters that differentiate the new nominal taxon from related or similar taxa.” Many newspaper articles, in addition to a general description, included explicit differentia– incisors, grooming toes– from related taxa, thus providing a diagnosis.

3bi) Can newspapers provide a public and permanent scientific record? In my post, I considered that the newspaper articles might be discounted, because perhaps they had not been issued “for the purpose of providing a public and permanent scientific record” (Art. 8.1.1). Some commenters have taken the position that this is self-evidently the case, but it’s not crystal clear to me.  The Code has always been loath to mandate specific formats of publication, specifying rather general properties (availability, simultaneity, identity, etc.) that a variety of formats might fulfill.  Historically, a huge variety of things have counted as publications (although no newspaper examples come to mind). Some newspapers have science sections, some are “papers of record”; I think the spirit of the Code is to approach each case on its individual merits. That is why the Code urges authors and editors to avoid anything that might make the situation murky, but it does so through recommendations (see my previous post for the specific recommendations).

3bii) Doesn’t the Code try to avoid “accidental” publication? Yes it does, as several commentators have pointed out. It has added meeting and symposium abstracts to the list of formats that are not permissible (Art. 9.9) to help avoid what the Code calls “unintentional publication”; but newspapers, as such, are not mentioned. The Code also now requires that the intention to establish a new name be explicit (Art. 16.1). This article is intended to prevent new names, especially a replacement name (nomen novum) to be introduced without mention, en passant if you will. Unfortunately, the newspaper articles make it absolutely clear that a new nominal taxon has been discovered and is being given a new name, and that this is the intention of the authors (on which, see next paragraph).  The Daily Mail article even uses the word “christened”. The Code urges authors to use “sp. nov.” or some other appropriate indication (Rec. 16A), but, again, does not require it. The Code recommends that any appearance of a new name in a work prior to its intended publication be accompanied by a disclaimer, making the new name unavailable (Art. 8.2 and Rec. 8D). The Daily Mail article contains the phrase “a scientific study to be published”: this might be taken to be such a disclaimer, and while it’s not as clear as one might want, it’s perhaps the most straightforward way of discounting the Daily Mail article. Such phrases may (or may not) appear in the other newspaper articles.

3biii) If it has been published elsewhere, who is the author of the name? The Code provides that when it is clear from the contents of a publication that the name and the conditions that make it available other than publication (i.e. the description or diagnosis) are the work of a person(s) other than the author of the publication, then the author of the name is the other person (Art. 50.1.1). In this case, the newspaper articles make clear that the name and its description were provided by someone else, many mentioning Jorn Hurum and Phil Gingerich. They (or whoever is mentioned in the earliest article published) are thus the authors.  This is a good thing, because it gives credit to at least some of the people actually involved in the work. The newspaper reporter would not be the author of the name.

To summarize the question of publication, the name has not been published in Plosone, but it may have been published in a newspaper. I hope the latter is not the case, and perhaps the Commission could issue a clarifying opinion (following an appropriate application) on the status of names published in newspapers (the problem may be distinguishing newspapers from newsletters from cheaply printed bulletins, and so on).

There are some other issues that have been discussed– the merits of paper vs. the web, the nature of peer review– but these go well beyond the particulars of Darwinius, although it might provide a case study for some of these issues. But one of the take home lessons here is that the recommendations of the Code should be taken to heart, and authors and editors should ensure that works affecting nomenclature are “self-evidently published within the meaning of the Code“(Rec. 8B), and that new names should not appear in works prior to their intended publication, or, if they do, they should “contain a disclaimer (see Article 8.2), so that new names published for the first time therein do not enter zoological nomenclature unintentionally and pre-empt intended publication in another work” (Rec. 8D).

Update. While I was writing this, Carl Zimmer got a reply from the Executive Secretary of the ICZN. She confirms that posting on Plosone does not make a name nomenclaturally available. The issue of the newspaper publication was not addressed; I’m not sure if Carl asked about this. I’m leaning myself toward the idea that inclusion of the statement that the study is going to appear somewhere else could be construed as a disclaimer, thus avoiding newspaper publication of the name (I’m still not sure that all newspaper articles included such a statement).

Update 2. Carl Zimmer at the Loom has a nice account of the PR run-up to the press conference, which he titles “Science Held Hostage“. And, also from Carl, Plosone has today printed a 50 copy paper edition. If we can dismiss the newspaper versions (which, as I indicate in my first update, I think we can because they can be plausibly interpreted to have a disclaimer), then the name is now published with the intended authorship; the date of publication is 21 May 2009 (not 19 May, which is when it was posted to the web). Carl also succinctly explains why the nomenclatural rules are necessary:

To those not steeped in species, genera, suborders and suprafamilies, all of these bylaws and codes may trigger vertigo. But keeping the world’s biodiversity in order is not for the faint of heart. With 1.8 million species on the books, and tens of thousands of new ones being added every year, taxonomists need an intricate set of rules to keep it all straight. The fact that taxonomists share a set of rules, no matter how intricate, was one of the great advances in the history of biology.

Has the name Darwinius masillae been published? And if so, by who?

May 20, 2009 • 1:27 pm

by Greg Mayer

In a previous post on the hype surrounding the online posting of a paper on ‘Ida’, the Eocene primate from the Messel Lagerstatte, I noted that the

from Hurun et al. 2009. Plosone. www.plosone.org
from Franzen et al. 2009. Plosone. http://www.plosone.org

authors had made a nomenclatural faux pas in allowing the name and a description to be published before their paper appeared, thus making the authorship and date of publication of the name murky. At Laelaps, cromercrox (comment 35 here and comment 16 here), and at the Loom, Martin Brazeau and Larry Witmer (comments 27 & 29) have also noted nomenclatural problems, since online posting does not constitute publication under the International Code of Zoological Nomenclature, unless copies “have been deposited in 5 major publicly accessible libraries which are identified by name in the work itself”, (ICZN 8.6), which didn’t happen. As posted by Plosone, the paper is not published for nomenclatural purposes.

My concern was not that the name was unpublished, but that it had already been published, in one or more of the newspapers or perhaps even magazines that covered the pre-press conference hoopla. In the Code, Article 8 defines publication, Articles 10 and 11 cover general conditions of availability of a name, and Article 13 gives the particulars for names published after 1930 (the rules are stricter after 1930). The requirements may be summarized by saying that a proper new name must be published (sensu Article 8), and must “be accompanied by a description or definition that states in words characters that are purported to differentiate the taxon” (ICZN 13.1.1). I fear these requirements have been met by some of the pre-press conference articles.

The earliest one I have found is the one in the Daily Mail from May 10 (there may be earlier ones– I haven’t looked very hard). (I also don’t have a paper copy, and am assuming the web article appeared in the paper.  If it didn’t, I could illustrate the exact same points for the New York Times, for which I do have paper copies.) In the article, by Sharon Churcher, the name appears:

Christened Darwinius masillae, it belonged to an extinct group of primates which lived in rainforests.

It also includes characters that are purported to differentiate the taxon:

The study’s authors insist that the fossil can’t be a lemur because it lacks two features: the ‘toothcomb’, a set of lower front teeth used to groom fur; and ‘toilet claws’, toes on the hind feet used for scratching.

The Mail is also mass produced in identical copies obtainable for free or by purchase, publicly available, and permanently archived in many libraries. So it looks like the name has been published.  The one possible out is that you could argue that the Mail isn’t issued for the purpose of providing a scientific record, but purposes are slippery things. Does a newspaper with a science section (which is of course quite purposeful) meet the requirement, but perhaps one without doesn’t? I don’t know. That’s why it’s murky. It is to avoid murkiness that the Code makes Recommendation 8B:

Authors and publishers are strongly urged to ensure that a new scientific name or nomenclatural act is first published in a work printed on paper.

also Recommendation 8D:

Authors, editors and publishers have a responsibility to ensure that works containing new names, nomenclatural acts, or information likely to affect nomenclature are self-evidently published within the meaning of the Code. Editors and publishers should ensure that works contain the date of publication, and information about where they may be obtained. (emphasis added)

and Recommendation 8E:

Editors and publishers should avoid including new names and the information that might appear to make the names available, or new nomenclatural acts, in works that are not issued for public and permanent scientific record (such as pre-symposium abstracts, or notices of papers to be delivered at a meeting). They should ensure that such documents contain a disclaimer (see Article 8.2), so that new names published for the first time therein do not enter zoological nomenclature unintentionally and pre-empt intended publication in another work. (emphasis added)

But it looks to me like the Mail (or the Times, or whoever published it first) is the first valid publication of the name. The Code provides that the author of a name need not be the author of the work:

However, if it is clear from the contents that some person other than an author of the work is alone responsible both for the name or act and for satisfying the criteria of availability other than actual publication, then that other person is the author of the name or act. If the identity of that other person is not explicit in the work itself, then the author is deemed to be the person who publishes the work. (ICZN 50.1.1; emphasis added)

Jorn Hurum and Phil Gingerich are mentioned in the article as people who did the work, with Hurum given precedence.  So what’s the proper citation of this new taxon? It’s

Darwinius masillae Hurum and Gingerich in Churcher 2009.

Paleontology and the media

May 19, 2009 • 12:15 am

by Greg Mayer

The New York Times is reporting some major media event at the American Museum of Natural History on Tuesday concerning a 47 million year old primate fossil from Germany.  There’re reports of secrecy, exclusivity, and high priced documentaries. It seems a tad curious, since by available reports, the American Museum has nothing to do with the research or the fossil, which is in the collection of the Natural History Museum in Oslo, and the fossil was already reported on by the Times a few days ago and by the Daily Mail over a week ago. The fossil is from the Messel shale an important lagerstatte. Keep an eye out for the reports later today.

(PS The American Museum has what seems to be a really neat new mammal exhibit, reviewed here.  If you’re in New York, go see it.)

Update. The press conference has been held. The BBC has a few videos here. The specimen is a very well preserved, nearly complete, articulated skeleton, with remnants of fur and stomach contents (as is often the case in specimens from the Messel Lagerstatte), of a basal higher primate (i.e. near the ancestry of monkeys, apes, and man). The authors of the paper made a taxonomic faux pas in allowing the name of the new creature, along with a description, to be published prior to the appearance of their paper. The authorship of the name, and its date of publication, are now murky.

Update 2. As I feared, a big media roll out is not always conducive to getting the story right.  Just now on the Rachel Maddow Show, the features reporter said that the new primate might be the missing link between man and ape. It is of course nothing of the sort, and the authors never said it was, but using the term “missing link” as the key descriptor of the find (see the Daily Mail link above for an example) was bound to lead to some such misunderstanding. He also stressed that it could be “upright”, which many may take to mean bipedal, but, of course, it wasn’t. Laelaps and PZ concur about the doleful effects of the media hype. More from Laelaps here. The hype is even more overheated than I realized: from the promoters: “WORLD RENOWNED SCIENTISTS REVEAL A REVOLUTIONARY SCIENTIFIC FIND THAT WILL CHANGE EVERYTHING | Ground-Breaking Global Announcement”. Money quote from Laelaps:

I have the feeling that this fossil, while spectacular, is being oversold. This raises an important question about the way scientific discoveries, particularly fossil finds, are being popularized. Darwinius is just the latest is a string of significant fossils to be hyped in the media before being scientifically described (or at least before that information is released to the public). Other recent examples include “Dakota” the Edmontosaurus, the pliosaur “Predator X“, and “Lyuba” the baby mammoth. I am glad that these finds are stirring excitement, but I am a bit put off by the way they are presented.

Update 3 (May 20). Carl Zimmer and Ed Yong add to the critical pile on. A sample of Ed Yong’s wonderful satirical evisceration:

Around the world, signs that everything has changed have already begun to appear. Jeanette Gould from Stoke-on-Trent was shocked to discover the outline of Darwinius emblazoned on her morning toast. “Well, it ruined breakfast,” said Ms Gould, failing to appreciate the detail of the creature’s stomach contents outlined in bread crumbs. “I couldn’t very well spread raspberry jam over the direct ancestor of my children, could I?”

There is a wonderful accompanying illustration of the piece of toast.

Why the evolution of humans was NOT inevitable; BioLogos peddles more dubious science

May 13, 2009 • 7:21 am

Over at that hilarious goldmine of accommodationism, Francis Collins’s BioLogos website (generously supported by The Templeton Foundation, they have posted an answer to the question, “Did evolution have to result in human beings?” Now if you know anything about this history of faith/science accommodationism, you know that the answer has to be “yes”, at least if you construe the question to mean “Did evolution have to result in a rational, highly intelligent being that was capable of apprehending and worshiping its creator?”  If God is running the evolutionary process, as the accommodationists maintain, then the evolution of humans (who are, after all, the goal of this process — the one species made in God’s image) could not have been left to chance.

And so, religious biologists like Kenneth Miller and Francis Collins, and “science-friendly” theologians like John Haught, have maintained in their writings that evolution would inevitably have coughed up an intelligent rational creature like Homo sapiens.  In other words, contrary to the assertions of Stephen Jay Gould, if we re-ran the tape of life, something humanlike would always appear.  Religious apologists always contend that the evolution of what we will call “humanoids” was not a continent process: it was built by God into the very fabric of evolution.

Of course, this is not a scientific belief.  For one thing, it makes humans different from other creatures.  The faithful don’t go around maintaining that the evolution of squirrels or cockroaches was an inevitable outcome of the evolutionary process, because according to Scripture God didn’t make rodents of insects in His image.  So God stuck his hand in, somewhere, to make humanoids appear.  That is creationism, pure and simple.  Or, he designed the process with the foreknowledge that humans would appear, which is also creationism, since no evolutionist really thinks that the process was jerry-rigged from the outset to produce certain life forms.

Second, if you do believe in a naturalistic and materialistic process of evolution in which God didn’t interfere, then the appearance of humans doesn’t seem likely at all — and certainly not inevitable.  Higher intelligence and rationality evolved only once, so it certainly isn’t something like eyes (whose morphology evolved independently dozens of time).  The idea that “convergent evolution” shows that humans were inevitable is deeply fallacious.

Yet BioLogos uses this argument — a favorite of the religious paleontologist Simon Conway Morris –to show that (surprise!) something like humans WAS inevitable in evolution.  After disposing of Gould’s contingency argument, they then approvingly reiterate Conway Morris’s “convergence” argument:

Humans: Inevitable, Intentional

Simon Conway Morris presents a different perspective, arguing humans, or a human-like species, are actually an inevitable part of evolution.  Morris is not proposing a different mechanism for human evolution, merely a different observation of its possible outcomes.  Morris would agree that any slight difference in the history of human DNA would result in a different evolutionary path.  Unlike Gould, however, Morris argues each of those possible pathways would inevitably lead to something like the human species.  Morris writes:

“The prevailing view of evolution is that life has no direction — no goals, no predictable outcomes. Hedged in by circumstances and coincidence, the course of life lurches from one point to another. It is pure chance that 3 billion years of evolution on Earth have produced a peculiarly clever ape. We may find distant echoes of our aptitude for tool making and language and our relentless curiosity in other animals, but intelligence like ours is very special. Right?”

“Wrong! The history of life on Earth appears impossibly complex and unpredictable, but take a closer look and you’ll find a deep structure. Physics and chemistry dictate that many things simply are not possible, and these constraints extend to biology. The solution to a particular biological problem can often only be handled in one of a few ways, which is why when you examine the tapestry of evolution you see the same patterns emerging over and over again.”

The patterns Morris mentions are also referred to as convergences in the evolutionary process.  In his most recent book, Life’s Solution, Morris gives many examples of physical traits or abilities found repeatedly among different species.5 Normally, such similarities are understood asthe result of common ancestry.  However, the species in Morris’s examples are known to be distantly related.  In many cases, not even these species’ common ancestor shared the same trait.  The implication is that several different species have independently developed similar traits.

The examples of convergence range across many levels of biology.  One popular and straightforward example is the human eye.  It turns out that several other species share a nearly identical visual system to that of the human eye, including the octopus.6 However, humans and octopuses have separate predecessors, neither of which shared this characteristic.  Two very different evolutionary paths arrived at the same visual system.  If Gould’s supposition is correct, and there was an infinity of other possible outcomes, then this example of convergence is all the more improbable.  Morris’s argument, conversely, is that the laws of nature allow for only a few solutions to any particular problem.  It appears the eye has developed independently at least seven times over the course of evolutionary time.

Human Significance

To see evidence for human significance, one need only consider Morris’s examples of convergence for many of the traits that are particularly relevant for human-like beings.  These examples include basic senses like balance, hearing and vision, as well as highly advanced features like the human brain.  Morris argues that evolution does not pose any threat to human significance.  Characteristics such as a large brain capable of consciousness, language and complex thought would inevitably have to emerge from the evolutionary process. Morris writes:

“Contrary to popular belief, the science of evolution does not belittle us.  As I argue, something like ourselves is an evolutionary inevitability, and our existence also reaffirms our one-ness with the rest of Creation.” 7

The exact anatomical features of this ultimate sentient being might not be precisely specified by the evolutionary process, however.  This thought can be unsettling to anyone who imagines our particular body plan is part of the imago Dei, or image of God. Despite the marvelous paintings in the Sistine Chapel, there is no reason to think that God the Father has a physical body that looks like ours.

God’s Sovereignty in the Evolution of Humans

Belief in a supernatural creator always leaves open the possibility that human beings are a fully-intended part of creation.  If the Creator chooses to interact with creation, he could very well influence the evolutionary process to ensure the arrival of his intended result.  (See Question 14 about Evolution and Divine Action.)  Furthermore, an omniscient creator could easily create the universe in such a way that physical and natural laws would result in human evolution.  (See Question 19 about Fine-Tuning of our Universe.)

Although the unpredictable mutations of DNA can make any species appear entirely accidental, Simon Conway Morris also puts forward strong arguments in favor of the inevitability of creatures that have the attributes of humans.  From this perspective, it seems the evolutionary process itself might be geared toward human life.

So it goes. (By the way, have a look at the last paragraph of this page where BioLogos suggests that the evolution of humanoids ON OTHER PLANETS was  improbable. (As expected, they take this stand because theologists can’t see God sending Jesus careening from planet to planet to save every species of alien).

The Argument for the Inevitability of Humanoids is perhaps the most popular argument (ranking with The Fine Tuning of Physical Constants) used by accommodists to show that evolution and God are not in conflict.  But the argument is simply wrong.  Nobody can say with assurance that the evolution of humanoids was inevitable.  The only honest response is “We don’t know” (and I would add “what we know about evolution tells us that it was probably not inevitable.”)

I attacked this argument in my New Republic essay “Seeing and Believing,” and for those who haven’t read it, or who don’t wish to plow through the link to find it, I’ll reproduce it here. This was a review of two books, Kenneth Miller’s Only a Theory: Evolution and the Battle for America’s Soul, and Karl Giberson’s Saving Darwin: How to be a Christian and Believe in Evolution.

III.

In Finding Darwin’s God, his earlier book, Miller proclaimed a universal theism: “Remember, once again, that people of faith believe their God is active in the present world, where He works in concert with the naturalism of physics and chemistry.” Giberson clearly agrees. And where do they find the hand of God in nature? Unsurprisingly, in the appearance of humans.

Giberson and Miller assert that the evolution of humans, or something very like them, was inevitable. Given the way that evolution works, they claim, it was certain that the animal kingdom would eventually work its way up to a species that was conscious, highly intelligent, and above all, capable of apprehending and worshipping its creator. This species did not have to look perfectly human, but it did have to have our refined mentality (call it “humanoid”). One of Miller’s chapters is even titled “The World That Knew We Were Coming.” Giberson notes that “capabilities like vision and intelligence are so valuable to organisms that many, if not most biologists believe they would probably arise under any normal evolutionary process…. So how can evolution be entirely random, if certain sophisticated end points are predictable?”

Reading this, many biologists will wonder how he can be so sure. After all, evolution is a contingent process. The way natural selection molds a species depends on unpredictable changes in climate, on random physical events such as meteor strikes or volcanic eruptions, on the occurrence of rare and random mutations, and on which species happen to be lucky enough to survive a mass extinction. If, for example, a large meteor had not struck Earth sixty-five million years ago, contributing to the extinction of the dinosaurs–and to the rise of the mammals they previously dominated–all mammals would probably still be small nocturnal insectivores, munching on crickets in the twilight.

Evolutionists long ago abandoned the notion that there is an inevitable evolutionary march toward greater complexity, a march that culminated in humans. Yes, the average complexity of all species has increased over the three-and-a-half billion years of evolution, but that is because life started out as a simple replicating molecule, and the only way to go from there is to become more complex. But now complexity is not always favored by natural selection. If you are a parasite, for instance, natural selection may make you less complex, because you can live off the exertions of another species. Tapeworms evolved from free-living worms, and during their evolution have lost their digestive system, their nervous system, and much of their reproductive apparatus. As I tell my students, they have become just absorptive bags of gonads, much like the students themselves. Yet tapeworms are superbly adapted for a parasitic way of life. It does not always pay to be smarter, either. For some years I had a pet skunk, who was lovable but dim. I mentioned this to my vet, who put me in my place: “Stupid? Hell, he’s perfectly adapted for being a skunk!” Intelligence comes with a cost: you need to produce and to carry that extra brain matter, and to crank up your metabolism to support it. And sometimes this cost exceeds the genetic payoff. A smarter skunk might not be a fitter skunk.

To support the inevitability of humans, Giberson and Miller invoke the notion of evolutionary convergence. This idea is simple: species often adapt to similar environments by independently evolving similar features. Ichthyosaurs (ancient marine reptiles), porpoises, and fish all evolved independently in the water, and through natural selection all three acquired fins and a similar streamlined shape. Complex “camera eyes” evolved in both vertebrates and squid. Arctic animals such as polar bears, arctic hares, and snowy owls either are white or turn white in the winter, hiding them from predators or prey. Perhaps the most astonishing example of convergence is the similarity between some species of marsupial mammals in Australia and unrelated placental mammals that live elsewhere. The marsupial flying phalanger looks and acts just like the flying squirrel of the New World. Marsupial moles, with their reduced eyes and big burrowing claws, are dead ringers for our placental moles. Until its extinction in 1936, the remarkable thylacine, or Tasmanian wolf, looked and hunted like a placental wolf.

Convergence tells us something deep about evolution. There must be preexisting “niches,” or ways of life, that call up similar evolutionary changes in unrelated species that adapt to them. That is, starting with different ancestors and fuelled by different mutations, natural selection can nonetheless mold bodies in very similar ways–so long as those changes improve survival and reproduction. There were niches in the sea for fish-eating mammals and reptiles, so porpoises and ichthyosaurs became streamlined. Animals in the Arctic improve their survival if they are white in the winter. And there must obviously be a niche for a small omnivorous mammal that glides from tree to tree. Convergence is one of the most impressive features of evolution, and it is common: there are hundreds of cases.

All it takes to argue for the inevitability of humanoids, then, is to claim that there was a “humanoid niche”–a way of life that required high intelligence and sophisticated self-consciousness–and that this niche remained unfilled until inevitably invaded by human ancestors. But was its occupation really inevitable? Miller is confident that it was:

“But as life re-explored adaptive space, could we be certain that our niche would not be occupied? I would argue that we could be almost certain that it would be–that eventually evolution would produce an intelligent, self-aware, reflective creature endowed with a nervous system large enough to solve the very same questions we have, and capable of discovering the very process that produced it, the process of evolution…. Everything we know about evolution suggests that it could, sooner or later, get to that niche.”

Miller and Giberson are forced to this view for a simple reason. If we cannot prove that humanoid evolution was inevitable, then the reconciliation of evolution and Christianity collapses. For if we really were the special object of God’s creation, our evolution could not have been left to chance. (It may not be irrelevant that although the Catholic Church accepts most of Darwinism, it makes an official exception for the evolution of Homo sapiens, whose soul is said to have been created by God and inserted at some point into the human lineage.)

The difficulty is that most scientists do not share Miller’s certainty. This is because evolution is not a repeatable experiment. We cannot replay the tape of life over and over to see if higher consciousness always crops up. In fact, there are good reasons for thinking that the evolution of humanoids was not only not inevitable, but was a priori improbable. Although convergences are striking features of evolution, there are at least as many failures of convergence. These failures are less striking because they involve species that are missing. Consider Australia again. Many types of mammals that evolved elsewhere have no equivalents among marsupials. There is no marsupial counterpart to a bat (that is, a flying mammal), or to giraffes and elephants (large mammals with long necks or noses that can browse on the leaves of trees). Most tellingly, Australia evolved no counterpart to primates, or any creature with primate-like intelligence. In fact, Australia has many unfilled niches–and hence many unfulfilled convergences, including that prized “humanoid” niche. If high intelligence was such a predictable result of evolution, why did it not evolve in Australia? Why did it arise only once, in Africa?

This raises another question. We recognize convergences because unrelated species evolve similar traits. In other words, the traits appear in more than one species. But sophisticated, self-aware intelligence is a singleton: it evolved just once, in a human ancestor. (Octopi and dolphins are also smart, but they do not have the stuff to reflect on their origins.) In contrast, eyes have evolved independently forty times, and white color in Arctic animals appeared several times. It is hard to make a convincing case for the evolutionary inevitability of a feature that arose only once. The elephant’s trunk, a complex and sophisticated adaptation (it has over forty thousand muscles!), is also an evolutionary singleton. Yet you do not hear scientists arguing that evolution would inevitably fill the “elephant niche.” Giberson and Miller proclaim the inevitability of humanoids for one reason only: Christianity demands it.

Finally, it is abundantly clear that the evolution of human intelligence was a contingent event: contingent on the drying out of the African forest and the development of grasslands, which enabled apes to leave the trees and walk on two legs. Indeed, to maintain that the evolution of humans was inevitable, you must also maintain that the evolution of apes was inevitable, that the evolution of primates was inevitable, that the rise of mammals was inevitable, and so on back through dozens of ancestors, all of whose appearances must be seen as inevitable. This produces a regress of increasing unlikelihood. In the end, the question of whether human-like creatures were inevitable can be answered only by admitting that we do not know–and adding that most scientific evidence suggests that they were not. Any other answer involves either wishful thinking or theology.

Miller opts for theology. Although his new book does not say how God ensured the arrival of Homo sapiens, Miller was more explicit in Finding Darwin’s God. There he suggested that the indeterminacy of quantum mechanics allows God to intervene at the level of atoms, influencing events on a larger scale:

“The indeterminate nature of quantum events would allow a clever and subtle God to influence events in ways that are profound, but scientifically undetectable to us. Those events could include the appearance of mutations, the activation of individual neurons in the brain, and even the survival of individual cells and organisms affected by the chance processes of radioactive decay.”

In other words, God is a Mover of Electrons, deliberately keeping his incursions into nature so subtle that they’re invisible. It is baffling that Miller, who comes up with the most technically astute arguments against irreducible complexity, can in the end wind up touting God’s micro-editing of DNA. This argument is in fact identical to that of Michael Behe, the ID advocate against whom Miller testified in the Harrisburg trial. It is another God-of-the-gaps argument, except that this time the gaps are tiny.

Obviously, given that higher intelligence and rationality of the human type has evolved only once, the existence of convergence says nothing about whether these features would always appear.  In fact, the one-offness seems to imply otherwise.

What bothers me about this is, of course, that BioLogos is using the imprimatur of science (and the wonky ideas of Simon Conway Morris) to try to convince people that of course our evolution was inevitable.  This tactic is a favorite of BioLogos (and Templeton), for it tries to blur the boundaries between science and faith.  As scientists we can say nothing about the inevitability of humans except that it seems unlikely given its unique appearance.  Certainly one can say that the idea of evolutionary convergence is irrelevant here.

Please, BioLogos, stop making scientific arguments for God!

Hobbits are back, and they’re REAL!

May 7, 2009 • 1:11 pm

I’ve written quite a bit about the Homo floresiensis controversy: these are the small (1-meter tall) individuals whose remains were found in a cave on the Indonesian island of Flores, originally dated about 18,000 years old.  They are remarkable because of their size, their small brains (about the size of a chimp’s) and their remarkably recent age — a time when the much taller and brainier Homo sapiens had already infested the world.  But there was doubt about whether these diminuitive fossils represented a real species: some people thought that the one relatively complete skull represented a diseased or microcephalic individual.

Two papers in the latest issue of Nature (links below) address this controversy, and both come down on the side of H. floresiensis being a real species, not an aberration. (There’s also a very nice two-page summary by Daniel Lieberman if you don’t want to plow through the articles.)  More bones have been found in the Liang Bua cave on Flores (see below), most notably a pretty complete foot.  The foot, like the rest of the skeleton, shows an intriguing mixture of primitive and derived traits.  There are now enough bones to pretty much rule out the “aberrant individual” theory.

So what was H. floresiensis?  As the diagram below shows, it could have been a descendant of an earlier hominin species, H. habilis, or perhaps a very early form of H. erectus; in both cases it would have had to reach the island several million years ago.  Yet the brains of these two ancestors were larger than that of the hobbit, so how did it get such a small titer of gray matter? (Hobbit brains were about 400 cc in volume, the size of a modern chimp or of the smallest australopithecines.)  Here the notable dwarfism of many species on islands (including elephants on Flores) comes in: like other mammal species, H. floresiensis could simply be an evolutionarily dwarfed form of an earlier hominin. Weston and Lister’s paper gives relevant data taken, oddly enough, from dwarf hippos on Madagascar , but I’ll leave you to follow their reasoning in their article.

This is perhaps the most bizarre and interesting twist in hominin evolution yet, and it’s completely unsettled.  A whole new group of questions open up.   How did this weird species coexist with the much larger and brainier H. sapiens for so long?  (H. floresiensis was not dumb, by the way: they managed to colonize the island over water and made fairly sophisticated tools).  If hobbits are a remnant of the H. habilis lineage, how come we don’t find habilis fossils elsewhere outside of Africa?

The foot of Homo floresiensis.   W. L. Jungers, W. E. H. Harcourt-Smith, R. E. Wunderlich, M. W. Tocheri, S. G. Larson, T. Sutikna, Rhokus Awe Due & M. J. Morwood

Insular dwarfism in hippos and a model for brain size reduction in Homo floresiensis. E. M. Weston and A. M. Lister

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Ling Bua cave on Flores: where the hobbits were found.  Photograph by C. Turney, University of Wollongong

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Homo floresiensis might be most closely related to early H. erectus, but also shows potential affinities with H. habilis. In either case, recognizing H. floresiensis as a species will require us to re-examine how we define species of the genus Homo and how they were related to each other. Reasonably well-known relationships are indicated by solid arrows; less secure relationships are indicated by dotted arrows. Broken vertical bars indicate uncertainties about when species evolved or went extinct. (Figure and caption from Lieberman’s summary.)