Expanding the Human Family, One Cave at a Time
A couple weeks back on the blog, Callum Ross debunked a lemur-like creature, Darwinius masillae, purported by some to be a very distant human ancestor. If you were feeling sad about this contraction of the human family circle, you may have been cheered by news this week about the potential debut of a new, more human-like human ancestor. There is no fancy Latin name for this relative yet, because even the authors of the paper announcing its existence are unwilling to declare that an entirely new species has been found. But it’s enough to dream up some not entirely unscientific (and somewhat unsettling) daydreams of a time when what we know today as humans were not the only two-legged tool-using primates on the scene.
The uncertainty surrounding the finding published in Nature by Johannes Krause, Svante Paabo and colleagues is that the discovery was made with a little bit of paleontology and a lot of genetics. The human ancestors or cohabitants we’re more familiar with – like Neanderthals or Homo erectus – were discovered in skeleton form, the classical way scientists learn of extinct creatures. But Krause & company’s fossil findings are limited to a pinky bone discovered in a Siberian cave, dated to 40,000 years ago. Because you can’t tell much anatomically from a pinky bone, the researchers instead harvested DNA from the bone; specifically, mitochondrial DNA (mtDNA), a smaller stretch of genes inherited entirely from one’s mother. When compared to mtDNA from modern humans and Neanderthals, it was dramatically different from both species – roughly twice as different as the gap between humans and Neanderthals.
The authors (and most of the outside scientists I’ve come across online) reason that the most likely explanation for that difference is that the pinky belongs to a very old human-like species, one that may have branched off from modern humans 1 million years ago. There are other theories – Carl Zimmer proposes one alternate theory built on the rather salacious premise of interspecies lovin’ – but analysis from the nucleus DNA of the proposed new species is necessary to decide. In the meantime, it’s fascinating to think about a time when humans sort of like us had to compete with Neanderthals and whatever this new ancestor may have looked like for resources, much like different species of birds will fight over territory and food.
Oversimplifying the Gendered Brain
Louann Brizendine, a professor of psychiatry at UCSF, scored big-time success with The Female Brain in 2006, a book that focuses on how neuroendocrine differences between men and women may explain female behaviors. So it was inevitable that Brizendine would be back eventually with a sequel/counterpart, The Male Brain, which was just released and previewed this week in a guest column for CNN.com. Depending how you look at it, this is either at troubling or welcome development for science bloggers, who find a lot of material in dissecting Brizendine’s sometimes poorly-supported claims.
The Male Brain looks to be no less a content engine – Vaughan Bell at Mind Hacks found a pretty glaring error a mere three paragraphs into Brizendine’s CNN column when she attributed male behavior to a brain area that doesn’t even exist in humans. But it’s important to note that there’s more than just snark behind these criticisms. The most serious charge most critics apply to Brizendine is that she oversimplifies the sloppy complexity of the human brain, labeling various areas and hormonal states with gimmicky names (the “I feel what you feel” part of the brain, the “doting daddy” brain) that are good soundbites but bad science. Brizendine also tends to write authoritative statements about scientific conclusions that are far from proven – David DiSalvo at True/Slant points out that there are no papers supporting her theory of a “man trance” linking testosterone to ogling behavior.
But Brizendine is nothing if not flexible. When a Science study in 2007 disproved one of the main assertions of The Female Brain – that women use more words each day than men – she was hardly fazed. By the time I spoke to her for a Chicago Tribune article about the Science finding, Brizendine had already found a new spin, arguing that different environments of the workplace or home would expose more subtle sex differences in language use. Maybe so, but if the proof is not there, wrapping such bold, unsupported claims in scientific-sounding language may only reinforce harmful stereotypes while muddying the public’s knowledge about the brain.
If you’re looking for a more reliable science book, try Superbug by Maryn McKenna, a rather frightening exploration of community-acquired MRSA infections. The first wave of such infections was discovered by Robert Daum here at the University of Chicago, and that story features prominently in McKenna’s book. Listen to her interview on NPR’s Fresh Air here.
I don’t know if you heard this, but President Obama signed a sweeping health care reform bill this week. In the room for the signing was University of Chicago professor and public health expert Harold Pollack, who blogged about the experience at The New Republic.
Fast food takes on a new connotation as a study finds that McDonalds and Taco Bell logos increase people’s reading speeds and financial impatience. Ed Yong at Not Exactly Rocket Science breaks it down.
Are neuroscientists aiding the development of new “neural warfare” weapons by taking grant money from the Pentagon? John Horgan opines at Scientific American.