Telling what people think

Michael Egnor is confused.

No, wait, that's like saying that the Titanic is made of metal. Let's try again.

Michael Egnor's confusion is drowning him in his own turgid prose:

I can't tell what live people (or live rats) are thinking by looking at their brains, and I can't even tell using two-photon confocal microscopy (the latest in capillary imaging). Of course, I can't tell what dead people used to think by studying their brains, and I certainly can't tell what dead people used to think if I don't have a speck of tissue from their brains. And I certainly can't tell what 3.2 million year old hominids used to think by studying their skulls.

I can, however, tell what people are thinking by looking at what they write. Does anyone claim that they can tell what Lucy or other fossil hominids were thinking? No. However savagely Egnor assaults that straw-man, the real science of evolutionary biology remains unharmed.

While the Newsweek cover story in question is undeniably flawed, it does not make any such claim. The closest it comes is to point out how, "by comparing the impressions that brains left on the inside of skulls, 'paleoneurology' is documenting when structures that power the human mind arose, shedding light on how our ancestors lived and thought." How our ancestors thought is rather different than what they thought. How they thought involves seeing what parts of the brain were developing at what points. The link between parts of the brain and particular thought processes doesn't take confocal microscopes or knowledge of capillaries.

Alas, Dr. Egnor would rather preen about his knowledge of blood flow in the brain than actually understand or accurately present what scientists studying the evolution of the brain and the mind are doing.

It is no less unfortunate that the author of the Newsweek piece created a strawman of biological history. Ms. Begley speculates that "If you had asked paleoanthropologists a generation ago what lice DNA might reveal about how we became human, they would have laughed you out of the room."

A quick search of Google Scholar (I searched for: human anthropology ectoparasite) reveals that E. H. Hudson was considering "Treponematosis and Man's Social Evolution" in a research report published in 1965's American Anthropologist. Treponematosis isn't from a louse, but it is a broad category of parasitic infections which includes syphilis. He pointed out in 1965 that the spread of syphilis through casual contact was most likely to proceed rapidly within villages, so understanding the distribution of so-called "endemic syphilis" was one way to estimate the pace of urbanization in different regions.

The hypothesis seems to still be popular in modern anthropology, and to yield new insights into human evolution. Understanding how that disease evolved with human behaviors gives us insights that could be applied to other emerging diseases. Not only wouldn't anthropologists have laughed at the idea of using parasites to learn about human evolution, they were doing it, to the benefit of medical science as well.

The Journal of Biogeography published a paper in 1989 about the biogeography of the human flea, a paper which cites descriptions dating back to the 1920s of fleas in mummies and other ancient burials. Tracing those fleas reveals patterns in human migration, and reveals trade and contacts between human societies. If you consider twenty years to be a generation, we can agree that Buckland and Sabler's paper also puts the lie to Ms. Begley's description.

Begley also misrepresents science in this passage:

Although we tend to see the march of species down through time as a single-file parade, with descendant succeeding ancestor in a neat line, the emerging science shows that the story of our species is far more complicated than Biblical literalists would have it—but also more complex than secular science suspected.

It's true that the popular understanding of evolution often emphasizes those sequences of fossils which seem to lead in unbranching paths, with humans at one end and a straight line leading to our ancestor, that is not how biologists thing about it. I can't locate the quotation now, but I remember Stephen Jay Gould regularly berating this conception of evolution, both for its implicit and unjustified teleology but because it ignores the fundamentally bushy nature of evolutionary trees. In a historically contingent evolutionary process, the line connecting A to B is rarely straight, and biologists have known that for a century or more.

That misunderstanding is fundamental to the creationist error. It is why Behe's conception of irreducible complexity fails. He tries to falsify a straight line connecting points, then expresses surprise when people present more realistic evolutionary pathways. It is also why Egnor's egnorance is so dangerous. Diseases evolve along circuitous paths as well, and human anatomy is a product of circuitous pathways as well. To understand how the body fails, it's important to know how those flaws could have been advantageous at one time, or could be by-products of a different era.