The other day, BBC Radio 4 presented a half-hour show hosted by Adam Rutherford: “Human evolution versus cultural evolution,” the first of a two-part series called “In our own image: evolving humanity”. You can hear the show at the link, and I understand it will be up for a week.
The show features evolutionary luminaries discussing the role of genetic versus cultural evolution in the formation of our own species: these talking heads include Steve Jones, Steve Pinker, Kevin Laland, Steve Stearns, and my own Chicago colleague Anna di Rienzo.
If you’ve been following this website regularly, you won’t learn a lot that is new, but you may want to listen if you’re not up to speed on the question of whether and how much humans are still evolving, which is the topic of this show.
The participants have different takes. Most say “yes,” though Steve Jones, as always, claims that both the evidence for and the scope of genetic evolution in modern Homo sapiens is limited. He argues that since our divergence for the lineage that led to modern chimpanzees, human ancestors have evolved more slowly than those of chimps, and that the evolutionary changes in our ancestry mostly involve losses (e.g., hair). That, of course, neglects the tremendous cognitive gain that we’ve experienced. Jones also argues that the opportunity for selection, which involves variation in both longevity and offspring number (“reproductive success”), has also decreased drastically due to improvements in health care and sanitation.
As I’ve discussed before, Steve Stearns and his colleagues have argued otherwise using the long-term data from the Framingham Heart Study. Contrary to Jones, they claim that there is still sufficient variation among couples in offspring number to lead to substantial selection on health-related traits.
Steve Pinker talks about cultural versus genetic evolution; it may surprise some that he’s not a diehard evolutionary psychologist here, and argues that traits like music-making might not have been the direct object of selection, but rather evolutionary byproducts of other evolved cognitive capabilities. (Some evolutionary psychologists have claimed that traits like art and music were the direct objects of selection, since proficiency in those arts conferred on those higher reproductive success.)
Kevin Laland discusses the recent evidence in the genome for selection on humans; this involves population-genetic analysis of “selective sweeps,” which can detect signatures of natural selection by looking at the diversity of DNA variation around various genes. Low diversity in a region indicates that a nearby gene has recently undergone a “fixation,” that is, a single “allele,” or gene copy, has risen to high frequency from one or a few original mutations. See my previous post on this work.
Spencer Wells talks about genetic changes due to migration, concentrating on genes affecting skin pigmentation. He fails to mention, though, that that this story is still not well understood, and that there’s controversy about the classic “melanoma versus vitamin D” explanation.
Finally, Anna di Rienzo discusses her lab’s work on the Duffy antigen showing recent selection for malaria resistance, and talks about work on other “disease genes.”
It’s a good short summary for the layperson. I love the eloquence of these scientists, as well as the timbre of Pinker’s voice and Steve Jones’s hybrid Welsh/English accent (his take on a Cro-Magnon man riding the bus in Camden Town is hilarious). My only plaint: there could have been a bit more discussion of evidence for evolution via cultural change, that is, the “gene-culture coevolution” as exemplfied by the evolution of lactose tolerance in pastoral human populations (I talk about this in WEIT, and have posted on it here.
The question about evolution I get most often when talking to the general public is this: “Are humans still evolving?” If you can’t answer that question, you’ll be able to after a half-hour investment in listening to the show.
h/t: Dom
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This is the second time that my browser shows that you posted something, but all I can see is the word [subscribing]. Is there text that I can’t see?
People post [subscribing] when they do not wish to post a comment but want e-mail notification to read comments.
Thank you. I’ve learned something new.
Oh, no — that’s exactly what I typed.
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Cheers,
b&
Stiil, the idea of Ben not having anything to say on a subject is a bit mind- boggling.
Hey! My SIWOTI isn’t that bad, is it?
b&
Well, ACTUALLY…
No, clearly it’s not that bad. Now, just wait a bit while I write a 500-word essay proving my case….
b&
I had to look SIWOTI up, and in the Urban Dictionary I found:
Acronym for “someone is wrong on the internet.” Describes the compulsion to post rebuttals to online nonsense, in the vain hope that it will somehow set the record straight.
I try to stay away from Dinesh D’Souza’s ravings, but when you’ve got SIWOTI syndrome, the man is like a magnet of wrong. (PZ Myers, 3/April/2008)
Original source:
http://xkcd.com/386/
b&
My general reaction to the idea that modernity has stopped human evolution is that even if we assume that better health care, etc., has removed or significantly decreased all selective pressures on H. sapiens (and of course there are solid reasons to believe this is not the case anyway) we’re still only talking a period that would be measured in the thousands of years, and that’s if we’re being generous.
I daresay that if some dozens of millions of years ago, all selective pressure had been magically suspended for 1000 years and all gene pools held in perfect stasis, we surely wouldn’t be the wiser. It would be the tiniest blip, not detectable in the fossil record or probably even by molecular biology.
In order to believe that modern innovations have significantly retarded human evolution, we not only have to make assumptions about the effect of recent developments on relative reproductive success (assumptions which are looking increasing unlikely in the face of the data), but we also have to make wildly optimistic assumptions about the persistence of our civilization. Are we really willing to asset our civilization will be largely of the same character a million years from now???
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Are we really willing to asset our civilization will be largely of the same character a million years from now???
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I think most of the scientists that can think streight can see that our civilization has only about 100 – 200 years in the current form.
This is why I think the question of whether humans are evolving or not is very easy to answer: yes we do like all other life-forms: evolution never stops.
The question of whether it is “classical” evolutionory process or “cultural” is also answered very easily. It is neither.
The classical evolutionary process ended with arrival of homo species that evolved far enough as to have deliberative capability.
With this event the classical evolutionary process ended because homo sapiense has began introducing disruptions as part of its quest for survival and diasporation.
From a biological point-of-view this process is still under way. We still diasporate into all corner of the world. We continue “corrupt” all pre-sapience dynamics of the planet aacting as if we were outside of evolutionary process.
So the “classical” evolutionary process has ended with the arrival of homo sapience.
But evolution as biological process cannot be stopped and can also be viewed as _property_ of life-forms
It is very disturbing that all these prominent people do not talk about the fact that “cultural evolution” is only an artifact of thus-far intellectual development whereas evolution as property of life-forms is a fundamental biological concept.
It is very sad that they do not see how homo sapiens as species is yet to understand its own evolution as purely biological phenomenon but different from classical evolutionary process that was taking place before homo sapiens and its deliberative capability.
Mankind continues to bumble into inevitable understanding of how our civilization is funamentally primitive and does not reflect the proper understanding of nature and course of human evolution.
Mankind evolved out of ignorance. We continue to re-package ignorance in different words and “ideas”. And this is all while the speed of our “corruption” of pre-sapiens evolutionary dynamics increases.
And the scientists that are on top of the pecking order pyramid do not even mention these facts – they talk about “cultural evolution” that only distracts from proper understanding of nature and course of human evolution.
But this will not be like this for long.
Our civilization that evolved out of ignorance is unsustainable. And the civilization that would evolve out of science only exists at the moment as understanding of few scientists scattered thgruout the globe.
These scientists are naturally not in mainstream and will not get into the mainstream ever.
And they do not care to get into mainstream.
All they care that science continues ad is destined to be the sole guidance of human existens.
The genetic imperative to go on living that governs every life-form will take care of that.
Over deep evolutionary time-line.
What do you mean with “current form”? As regards biology, we are right now changing from disperse villages to urban living, last year or so passed the moment when most people live in cities.
This changes selective pressures, such as impressed stress and expressed anxiety.
Yes, yes, gloom and doom.
But here you are discussing something else entirely. Our civilization is changing, but that is the definitional character of modern civilization. Without incessant change it wouldn’t be so robust as it seems to be.
And the increasingly globalized civilization has become the happiest civilization ever. We passed “peak child” a few decades ago and with it (and the maximizing democratization) “peak woe”. You should go listen to some current statistics as presented by Rosling in his TED talks.
“And the increasingly globalized civilization has become the happiest civilization ever.”
Agreed. I never understood people who tend to be on the “Prophets of Doom”-team.
This simple catch-phrase pretty much sums up my own opinion.
“Bad things are getting worse, but good things are getting much better!”.
Almost everything follows these patterns.
I am no biologist, but surely there must have been other times in the history of the planet when selective pressures were reduced and a particular species enjoyed a few millennia of explosive growth. I doubt anyone would argue that the evolution of that species “stopped” during such a time.
This strikes me as a kind of species bias, or “we humans are so great we don’t even evolve anymore”.
IMO, we would expose a range of currently undefined and unexplored questions about human behavior, social organization, and evolution if it were not ubiquitously assumed (particularly by anthropologists, primatologists, and other social-science types) that (1) culture retards evolutionary processes in the human taxon and/or that (2) culture facilitates and/or fundamentally enhances phenotypic plasticity.
You could even claim assuming Jones was correct, that the momentary change in rate is evolution. =D
It’s the same old story. A bunch of scientists who seem to assume that “evolution” and “natural selection” are synonyms.
How much effort would it take to define evolution correctly, as they do, then briefly explain that much of evolution is due to random genetic drift? That kind of evolution can’t be stopped and the rate doesn’t change significantly. So the idea that humans might have stopped evolving is quite silly.
Then they could go on to say that the program will focus on adaptation, or evolution by natural selection. That’s a special part of evolution that’s of great interest to some evolutionary biologists.
Though here selection processes seems more important, since they are discussing “visible” characters. Also, and not coincidentally, seems easiest to measure.
Conversely, accordingly drift would not be questionable. But the faith of selection would be interesting.
In the developed world, we’ve largely decoupled sex from reproduction. For the first time, reproductive output is linked directly to the desire to have children. Surely that counts as a massive change in the selective landscape that (if it persists) cannot help but have evolutionary consequences.
great observation
unfortunately only very few people even in the west “deliberate” having or not having children
most of the people just “go with it” without thinking much why they may want or not want to have children, what it means to thewir quality of life and quality of life of their children and especially how their personal choice to have or not have children contributes to overpopulation
our civilization is not sustainable over very long term in the current form and is bound to evolve and this evolution will be guided by science
That’s not the only factor though.
The quality of life/medicine (for example in Western Europe) changed so drastically over the last 2-3 generations, that the infant mortality rate was 3 times higher 60 years ago. And while women give birth to less children at a later point in life, the average life expectancy of an Western European is over 80 years now and rising.
Another result of this, is that we grow taller. We are less sick.
What does that have to do with evolution?
Here the plot thickens. Our height changed so rapidly over the last 2-3 generations, that because the neck still has to support our big heads, an important bone in our skull starts to change its position in many children, in order to support the weight.
What will be the result of this? The skull starts to change its form and the brain will be positioned slightly different.
And? Well, it will gradually leave more room for the pre-frontal cortex to grow and slightly change the volume of the entire brain, which in return will probably lead to changes in its wiring and abilities.
Go back a few decades and ask, are pigeons, and dogs, and roses and cows, begonias and grain “still evolving”? The rapid pace of evolution of all these groups, and tons more, is due to the controlled “design” of traits by homo sapiens. H. Sapiens has, and will continue to advance, mechanisms to guide (dictate?) evolution, not only in numerous other species, but in H. Sapiens itself. Man will continue to evolve, not only by natural selection, but also by directed involvement in genetic manipulation. It will be interesting to posit what our input overlaid on the tide of evolution holds for the 25th, 30th and later centuries.
Problems with the “happy talk ” idea of contemporary human evolution includes:
– Evolution occurs in geological time so who cares?
– Just how, mechanically and genetically, would any mutation get dispersed to 7B++ ppl?
To us this kind if talk is simple denial, again, of genetic determinism which no one wants to accept.
If rate of population growth reflects average fitness in the population, or selective pressure on the population, then the the most fit, or least selected, populations are those with the highest rates of population growth. Among human populations these are found in what we would call the third world, not the developed world. So why aren’t the most successful human populations those with best health care, nutrition, wealth, safety, etc.?
You need two things for evolution, variation and differential reproductive success. Both of these are still around and contraceptives play an important role in the latter. I think we are seeing the rise of absentmindedness as those who forget to use contraception have more children than the more responsible sort! (LOL).
It’s too early to say really, but contraception has to be the most important evolutionary development since fire. Previously a high sex drive would mean more children (other things being equal), now it means nothing if you’re careful about condoms. Any characteristic which minimizes the use of contraceptives has to be a candidate for evolution to favour, but it’s all so complex it’s impossible to predict. I wish I was going to live long enough to see what happens.
Cochran
and Harpending argue in their recent book
“The 10,000 Year Explosion” (http://www.amazon.com/Why-Evolution-Is-True-ebook/dp/B001QEQRJW) that human evolution has actually experienced a significant speedup in the last 10,000 years.
The correct link: http://www.amazon.com/000-Year-Explosion-Civilization-Accelerated/dp/0465002218/ref=tmm_hrd_title_0?ie=UTF8&qid=1313657817&sr=1-1