Darwin caricatures.

Darwin’s views are often misrepresented to the point of caricature, as we all know, but there have also been plenty of examples of literal caricature of Darwin in the popular media. I recently gave some talks about evolutionary imagery, which included popular press cartoons from the 1800s that had a common theme of caricaturing Darwin as a chimp or having non-human apes exhibiting human characteristics and behaviour. This seems like as good a day as any (the 150th anniversary of the Origin, and all) to post my collection for your enjoyment.

[album: http://www.genomicron.evolverzone.com/images/albums/DarwinCaricature/]


From the Max Planck Institute for Chemical Ecology comes a press release describing a paper in Nature about bacterial evolution…

Bacteria Expect the Unexpected
Organisms ensure the survival of their species by genetically adapting to the environment. If environmental conditions change too rapidly, the extinction of a species may be the consequence. A strategy to successfully cope with such a challenge is the generation of variable offspring that can survive in different environments. Even though a portion of the offspring may have a decreased chance to survive, the survival of the species as a whole is guaranteed. For the first time scientists have now observed the evolution of such a strategy under lab conditions in an experiment with the bacterial species Pseudomonas fluorescens: A bacterial strain exposed to rapidly changing environmental conditions developed the ability to generate variable offspring without additional mutations. This new strategy ensured the survival of the bacterial strain. The results were published in NATURE. (05.11.2009).


Nature vs. hype.

From today’s Nature, an editorial entitled Mind the spin:

Scientists — and their institutions — should resist the ever-present temptation to hype their results.

[skipping to the money quote…]

…the temptation for scientists and their institutions to spin their research to the media, or to go publicity-mongering, is always there. And — as illustrated by the excessive public-relations campaign surrounding Ida, a fossil presented as a missing link in human evolution — too many in the media will buy into the initial hype.

Such behaviour is corrosive to the process of scholarly scientific communication. Research institutions must not allow it to become the norm.

Discovering Ardi — my thoughts.

I liked it.

Overall, I think the Discovery Channel did a good job of capturing the painstaking work that goes into scientific research, in this case spanning more than 15 years from discovery to publication. Some other quick thoughts:

  • This was not hype. If anything, it was pretty modest, given the amount and significance of the work involved. I didn’t see the Darwinius special, but even the previews had me wincing.
  • Mike Rowe is an excellent narrator. I have enjoyed his work when I have watched Deadliest Catch and Dirty Jobs, but I would also like to see (er, hear) him on more specials like this in the future. Mike, if you happen to read this, nicely done.
  • The special did a fine job of emphasizing over and over what needs to be emphasized over and over: we are not descended from chimps, we share a common ancestor with chimps.
  • This isn’t so significant as evidence for the fact of human evolution — we had plenty of that before. This is an important find that illustrates more about the path of human evolution.
  • I am not sure I entirely see why Ardi necessarily shows that the common ancestor was not chimp-like (knuckle-walking and large canine teeth could have been lost after the split), but I will see if this is made more clear in the actual papers. Nonetheless, no one should have assumed the common ancestor must have been very similar to a chimp — that assumption is based on a poor grasp of phylogenetics, basically.
  • The show could probably have been about 1/2 hour shorter. I enjoy seeing reconstructions, and I appreciate that they showed how this is done (I go through this briefly in one of my lectures as well, and I also liken it to forensic reconstruction). However, this did seem to imply a little more than I would have liked that coming up with a digital animation was the culmination of the work rather than an interesting aside.
  • They could have done without the just-so story about pair bonding and carrying food. I guess viewers would prefer some idea, and they did mention that there were many previous hypotheses, but if I had one significant complaint about the special it’s that this part was really speculative and not up to the standard of the rest of the meticulous research depicted otherwise.

Humans vs. chimps — neither is an offshoot.

Tomorrow’s Science will be a special issue reporting tons of new information on the fossil hominid Ardipithecus ramidus (“Ardi”), which is really exciting (though not as much as Darwinius, which was “like a meteor hitting the Earth” or whatever).

There are news reports of course, including one at USA Today that I want to comment on briefly:

The analysis of Ardipithecus ramidus (it means “root of the ground ape”), reported in the journal Science, changes the notion that humans and chimps, our closest genetic cousins, both trace their lineage to a creature that was more like today’s chimp. Rather, the research suggests that their common ancestor was a walking forest forager more cooperative in nature than the competitive, aggressive chimp…

[So far, so good, but then…]

…and that chimps were an evolutionary offshoot of this creature.

Nope. Neither humans nor chimps are offshoots of this creature, they are (if the phylogenetic assumption is correct) both descendants of a creature similar to this (but probably not this one per se). Otherwise it’s like arguing that your cousin is an offshoot of your grandmother and you’re not.

Luckily, one of the authors is quoted as giving a more reasonable interpretation:

So that could mean that while humans didn’t diverge much from their evolutionary ancestors, “chimps and gorillas look like really special evolutionary outcomes,” says Science study author Owen Lovejoy of Ohio’s Kent State University.

Right. This would make many of the obvious traits of chimps derived rather than primitive, and many classically human traits primitive rather than derived. (It doesn’t really matter in one sense, because every species is a mixture of primitive and derived traits, but it sure would destroy those evolutionary lineups with chimps at one end and humans at the other).

Much to no one’s surprise, Carl Zimmer presents a good story on the topic:

Chimpanzees may be our closest living relatives, but that doesn’t mean that our common ancestor with them looked precisely like a chimp. In fact, a lot of what makes a chimpanzee a chimpanzee evolved after our two lineages split roughly 7 million years ago. Ardipithecus offers strong evidence for the newness of chimps.

Only after our ancestors branched off from chimpanzees, Lovejoy and his colleagues argue, did chimpanzee arms evolve the right shape for swinging through trees. Chimpanzee arms are also adapted for knuckle-walking, while Ardipithecus didn’t have the right anatomy to lean comfortably on their hands. Chimpanzees also have peculiar adaptations in their feet that make them particularly adept in trees. For example, they’re missing a bone found in monkeys and humans, which helps to stiffen our feet. The lack of this bone makes chimpanzee feet even more flexible in trees, but it also makes them worse at walking on the ground. Ardipithecus had that same foot bone we have. This pattern suggests that chimpanzees lost the bone after their split with our ancestors, becoming even better at tree-climbing.

Chimpanzees do still tell us certain things about our ancestry. Our ancestors had chimp-sized brains. They were hairy like chimps and other apes. And like chimps, they didn’t wear jewelry or play the trumpet.

But then again, humans turn out to be a good stand-in for the ancestors of chimpanzees in some ways–now that Ardipithecus has clambered finally into view.

See also:

CSI: Common Scientific Illiteracy.

I don’t watch CSI. Ok, that’s not totally true or this post wouldn’t exist. I almost never watch it. I did catch a re-run while I was eating lunch on the weekend, an episode called “Overload” (some guy was electrocuted and fell off a building — I can’t exactly remember why).

In one scene, the lead character says, in what I assume is his typical “know it all” tone, “Terminal velocity is 9.81 metres per second per second”.

No, it ain’t — the acceleration due to gravity (on Earth) is 9.81 m/s2. The second time unit gives it away — this isn’t a velocity, it is a rate of change of a velocity.

So what?

Well, any kid in high school physics could have picked out that error. But here we have a screenwriter (probably a team of them), a director, producers, all the actors, sound techs, cameramen, editors, and post-production people involved in the scene, and evidently not one of them knows even the most basic physics concepts. More seriously, the producers of the show must assume that it doesn’t matter whether basic facts are checked because the audience is likely similarly uninformed. This really isn’t artistic license, and it adds nothing to the drama. It’s just a goofy mistake that could have been prevented — as Carl Sagan recommended in The Demon-Haunted World — by hiring a grad student to check the script.

Nitpicking? Maybe. But I think it’s a sad situation when no one involved in a science-themed show is even qualified to nitpick.

Kill or Cure?

This is too funny. A website called Kill or Cure? has been compiling links to science stories in The Daily Mail (UK) and their apparent “ongoing effort to classify every inanimate object into those that cause cancer and those that prevent it”.

A snippet of the entries under “M”…

The Junk DNA myth strikes again (next up: media hype).

Here’s the abstract of a paper set to be published in Molecular Biology and Evolution. Now, I think this kind of study is interesting and important. But it’s predictable that they start out with the standard (and historically false) claim that “non-coding DNA was long dismissed as junk” (seriously, do reviewers require authors to insert this line or something?). It’s also predictable that the amount of non-coding DNA that they report as showing signs of constraints (about 5% of the genome) will be reported in science news as “junk DNA functional after all!”.

Distributions of selectively constrained sites and deleterious mutation rates in the hominid and murid genomes.
Eory L, Halligan DL, Keightley PD

Protein-coding sequences make up only about 1% of the mammalian genome. Much of the remaining 99% has been long assumed to be junk DNA, with little or no functional significance. Here we show that in hominids, a group with historically low effective population sizes, all classes of non-coding DNA evolve more slowly than ancestral transposable elements, and so appear to be subject to significant evolutionary constraints. Under the nearly neutral theory, we expected to see lower levels of selective constraints on most sequence types in hominids than murids, a group that is thought to have a higher effective population size. We found that this is the case for many sequence types examined, the most extreme example being 5′ UTRs, for which constraint in hominids is only about one-third that of murids. Surprisingly, however, we observed higher constraints for some sequence types in hominids, notably four-fold sites, where constraint is more than twice as high as in murids. This implies that more than about one-fifth of mutations at four-fold sites are effectively selected against in hominids. The higher constraint at four-fold sites in hominids suggests a more complex protein-coding gene structure than murids, and indicates that methods for detecting selection on protein coding sequences (e.g., using the d(N) /d(S) ratio), with four-fold sites as a neutral standard, may lead to biased estimates, particularly in hominids. Our constraint estimates imply that 5.4% of nucleotide sites in the human genome are subject to effective negative selection, and that there are three times as many constrained sites within non-coding sequences as within protein-coding sequences. Including coding and non-coding sites, we estimate that the genomic deleterious mutation rate U = 4.2. The mutational load predicted under a multiplicative model is therefore about 99% in hominids.

Update: See BIOpinionated for a silly critique and Sandwalk for a fine reply.

Mark Siddall on leeches, cooking, and cooking leeches.

Dr. Mark Siddall is a friend of mine who is a curator at the American Museum of Natural History and a world expert on leech evolution. He also likes to cook. Leeches, not so tasty it turns out.

He is the first researcher to be featured on PBS’s new web series, The Secret Life of Scientists. Check it out.

Interview on ABC News Now:

The Secret Life of Scientists:

And don’t forget this NOVA clip:

Breaking news: evidence for evolution found!

One of Doug Futuyma’s great quotes is this one:

“…no biologist today would think of publishing a paper on ‘new evidence for evolution’… it simply hasn’t been an issue in scientific circles for more than a century.”
– Futuyma, 1998 Evolution Biology, 3rd edition

Press officers are a different story. Here’s one from the University of California, Riverside:

Molecular decay of enamel-specific gene in toothless mammals supports theory of evolution

Biologists at the University of California, Riverside report new evidence for evolutionary change recorded in both the fossil record and the genomes (or genetic blueprints) of living organisms, providing fresh support for Charles Darwin’s theory of evolution. Read more

It’s a cool study, linking fossil and genomic data. But it’s not cool because it provides “fresh support for Charles Darwin’s theory of evolution”. This is about the historical path and genetic mechanisms of evolution — the fact has been well established for 150 years.

Here’s the actual abstract and author summary:

Vestigial structures occur at both the anatomical and molecular levels, but studies documenting the co-occurrence of morphological degeneration in the fossil record and molecular decay in the genome are rare. Here, we use morphology, the fossil record, and phylogenetics to predict the occurrence of “molecular fossils” of the enamelin (ENAM) gene in four different orders of placental mammals (Tubulidentata, Pholidota, Cetacea, Xenarthra) with toothless and/or enamelless taxa. Our results support the “molecular fossil” hypothesis and demonstrate the occurrence of frameshift mutations and/or stop codons in all toothless and enamelless taxa. We then use a novel method based on selection intensity estimates for codons (ω) to calculate the timing of iterated enamel loss in the fossil record of aardvarks and pangolins, and further show that the molecular evolutionary history of ENAM predicts the occurrence of enamel in basal representatives of Xenarthra (sloths, anteaters, armadillos) even though frameshift mutations are ubiquitous in ENAM sequences of living xenarthrans. The molecular decay of ENAM parallels the morphological degeneration of enamel in the fossil record of placental mammals and provides manifest evidence for the predictive power of Darwin’s theory.

Author summary
Enamel is the hardest substance in the vertebrate body. One of the key proteins involved in enamel formation is enamelin. Most placental mammals have teeth that are capped with enamel, but there are also lineages without teeth (anteaters, pangolins, baleen whales) or with enamelless teeth (armadillos, sloths, aardvarks, pygmy and dwarf sperm whales). All toothless and enamelless mammals are descended from ancestral forms that possessed teeth with enamel. Given this ancestry, we predicted that mammalian species without teeth or with teeth that lack enamel would have copies of the gene that codes for the enamelin protein, but that the enamelin gene in these species would contain mutations that render it a nonfunctional pseudogene. To test this hypothesis, we sequenced most of the protein-coding region of the enamelin gene in all groups of placental mammals that lack teeth or have enamelless teeth. In every case, we discovered mutations in the enamelin gene that disrupt the proper reading frame that codes for the enamelin protein. Our results link evolutionary change at the molecular level to morphological change in the fossil record and also provide evidence for the enormous predictive power of Charles Darwin’s theory of descent with modification.

I can see why the reporter got somewhat confused. But note what they say, as there is a subtle but important distinction: this provides evidence for the predictive power of evolutionary theory. This is news, because it is sometimes argued that evolutionary research is purely descriptive. Examples like this and the discovery of Tiktaalik in the type and age of rocks where an intermediate fossil was predicted to occur show just how strong modern evolutionary ideas are.

As evidence for the fact of evolution, though… *yawn* … just put it on the pile with all the rest.


Meredith, R.W., Gatesy, J., Murphy, W.J., Ryder, O.A., and Springer, M.S. 2009. Molecular Decay of the Tooth Gene Enamelin (ENAM) Mirrors the Loss of Enamel in the Fossil Record of Placental Mammals. PLoS Genetics 5(9): e1000634.


For descriptions of the study, see Ed Yong and Carl Zimmer (both among my top science writers list).

Here’s another one! Evolution still scientifically stable
(it also has a wicked typo: “they therefore stand as proof that Darwin’s theory of evolution breaks down at the molecular level,” Professor Lithgow said.”)