New work on an ancient mammal

June 9, 2009 • 5:39 am

With her usual journalistic panache, Natalie Angier reports today in the New York Times on new work on the echidna, otherwise known as the spiny anteater (there are four species in the genera Zaglossus and Tachyglossus). The species is bizarre because, like the platypus, it is one of the two groups of mammals that lay eggs — the monotremes.  And, like the  platypus, echidnas are found in Australia, but also in New Guinea. They are toothless, and, unlike other mammals except the platypus, the females produce milk not through teats, but through a hairy patch on the belly from which milk is lapped up by the young (this may represent the primitive state of mammary glands from which modern breasts evolved).  Unlike other mammals (but like birds), they have a single hole for excretion, sex, and egg-laying: the cloaca.

A paper by Muse Opiang in the Journal of Mammalogy reports on the long-beaked echidna from New Guinea, Zaglossus bartoni.  Several individuals were captured (no easy feat for these reclusive beasts: it took 500 man-hours just to find the first one!) and radiotracked to determine home range size.  Although the results — that home range size is variable among individuals, ranging from about 10 to 170 hectares (0.1 to 1.7 square kilometers) — aren’t terribly exciting to the nonbiologist, they are valuable in contributing to our knowledge of this rare animal.   Angier livens things up by telling the tale behind the paper:

Muse Opiang was working as a field research officer when he became seized by a passion for the long-beaked echidna, or Zaglossus bartoni, which are found only in the tropical rain forests of New Guinea and a scattering of adjacent islands. He had seen them once or twice in captivity and in photographs — plump, terrier-size creatures abristle with so many competing notes of crane, mole, pig, turtle, tribble, Babar and boot scrubber that if they didn’t exist, nobody would think to Photoshop them. He knew that the mosaic effect was no mere sight gag: as one of just three surviving types of the group of primitive egg-laying mammals called monotremes, the long-beaked echidna is a genuine living link between reptiles and birds on one branch, and more familiar placental mammals like ourselves on the next. . .

.. . . Reproductively, monotremes are like a VCR-DVD unit, an embodiment of a technology in transition. They lay leathery eggs, as reptiles do, but then feed the so-called puggles that hatch with milk — though drizzled out of glands in the chest rather than expressed through nippled teats, and sometimes so enriched with iron that it looks pink.

Monotreme sex determination also holds its allure. In most mammals, a single set of XX chromosomes signifies a girl, a set of XY specifies a boy. For reasons that remain mysterious, monotremes have multiple sets of sex chromosomes, four or more parading pairs of XXs and XYs, or something else altogether: a few of those extra sex chromosomes look suspiciously birdlike. Another avianlike feature is the cloaca, the single orifice through which an echidna or platypus voids waste, has sex and lays eggs, and by which the group gets its name. Yet through that uni-perforation, a male echnida can extrude a four-headed penis.

When I was a graduate student, I had the good fortune to encounter one of these creatures — an adult named Francis who lived in the Museum of Comparative Zoology at Harvard.  I used to walk downstairs to pet it on the non-spiny parts,  and found, as Angier notes, that it was a friendly and peaceful beast.

Enrich your world by reading Angier’s article!


baby echidna

Damn!  P.Z. has posted a cat again! I see him a cat and raise him a panda:


A bit more about catering to the faithful

March 25, 2009 • 11:18 am

While going through the Berkeley website Understanding Science (discussed yesterday), I found something more of interest.  It’s a page called “Astrology: Is it Scientific?”, which sets out a checklist of questions that the student should answer to see if astrology is indeed a science.  Here’s part of the checklist:

Here we’ll use the Science Checklist to evaluate one way in which astrology is commonly used. See if you think it qualifies as scientific!

Focuses on the natural world?
Astrology’s basic premise is that heavenly bodies — the sun, moon, planets, and constellations — have influence over or are correlated with earthly events.

Aims to explain the natural world?
Astrology uses a set of rules about the relative positions and movements of heavenly bodies to generate predictions and explanations for events on Earth and human personality traits. For example, some forms of astrology predict that a person born just after the spring equinox is particularly likely to become an entrepreneur.
Uses testable ideas?
Some expectations generated by astrology are so general that any outcome could be interpreted as fitting the expectations; if treated this way, astrology is not testable. However, some have used astrology to generate very specific expectations that could be verified against outcomes in the natural world. For example, according to astrology, one’s zodiac sign impacts one’s ability to command respect and authority. Since these traits are important in politics, we might expect that if astrology really explained people’s personalities, scientists would be more likely to have zodiac signs that astrologers describe as “favorable” towards science.1 If used to generate specific expectations like this one, astrological ideas are testable.
Relies on evidence?
In the few cases where astrology has been used to generate testable expectations and the results were examined in a careful study, the evidence did not support the validity of astrological ideas.2 This experience is common in science — scientists often test ideas that turn out to be wrong. However, one of the hallmarks of science is that ideas are modified when warranted by the evidence. Astrology has not changed its ideas in response to contradictory evidence.

The page concludes by saying:

Astrology is not a very scientific way to answer questions. Although astrologers seek to explain the natural world, they don’t usually attempt to critically evaluate whether those explanations are valid — and this is a key part of science. The community of scientists evaluates its ideas against evidence from the natural world and rejects or modifies those ideas when evidence doesn’t support them. Astrologers do not take the same critical perspective on their own astrological ideas.

It seems to me that some of the claims of many faiths are similar to those of astrology–the four ideas given above.  Religion focusses on the natural world (at least some of the time), purports to explain it, uses testable ideas (e.g., efficacy of prayer), and relies on evidence (Scripture, archaeological findings, etc.)  Like astrology, religion fails all of these tests.

I’m not trying to say anything portentous, except that scientists are really keen to denigrate astrology while at the same time bending over backwards to respect religion, even though there is the same amount of evidence supporting each.  This is a point that science writer Natalie Angier makes in her wonderful essay, “My God Problem.”

Consider the very different treatments accorded two questions presented to Cornell University’s “Ask an Astronomer” Web site. To the query, “Do most astronomers believe in God, based on the available evidence?” the astronomer Dave Rothstein replies that, in his opinion, “modern science leaves plenty of room for the existence of God . . . places where people who do believe in God can fit their beliefs in the scientific framework without creating any contradictions.” He cites the Big Bang as offering solace to those who want to believe in a Genesis equivalent and the probabilistic realms of quantum mechanics as raising the possibility of “God intervening every time a measurement occurs” before concluding that, ultimately, science can never prove or disprove the existence of a god, and religious belief doesn’t—and shouldn’t—”have anything to do with scientific reasoning.”

How much less velveteen is the response to the reader asking whether astronomers believe in astrology. “No, astronomers do not believe in astrology,” snarls Dave Kornreich. “It is considered to be a ludicrous scam. There is no evidence that it works, and plenty of evidence to the contrary.” Dr. Kornreich ends his dismissal with the assertion that in science “one does not need a reason not to believe in something.” Skepticism is “the default position” and “one requires proof if one is to be convinced of something’s existence.”

In other words, for horoscope fans, the burden of proof is entirely on them, the poor gullible gits; while for the multitudes who believe that, in one way or another, a divine intelligence guides the path of every leaping lepton, there is no demand for evidence, no skepticism to surmount, no need to worry.

A couple more points of clarification about the last post:

1.  I am by no means denigrating the worthwhile achievements of the National Academy of Sciences and the National Center for Science Education in pushing back the tide of creationism.  Their effects (especially the NCSE’s) in court cases and school-board hearings have had a real and positive effect on keeping evolution in the schools.  My beef is that these effects are temporary ones.  Creationism is like herpes: it keeps coming back again and again until you extirpate the root cause.  The court cases and school board hearings are outbreaks of herpes, which are stanched by our colleagues.  But until the underlying virus is extirpated (that is, the kind of faith that is incompatible with evolution), the outbreaks will continue to occur.

2.  The NAS and NCSE seem to always trot out the “religious scientists” or “scientific theologians” when they need to sell evolution: John Haught, Ken Miller, Michael Ruse, etc.  I would feel better about the whole issue if they’d also trot out Richard Dawkins, Daniel Dennett, and the many other evolutionists who represent a non-accommodationist point of view.

3.   By saying that we should leave the reconciliation of faith and science to theologians, I am not endorsing the idea that they can or should be reconciled.  Personally, I don’t think they can be. I’m saying only that that reconciliation is not the job of scientists or pro-evolution organizations.