Friday, February 27, 2009

Hominid highlights (or, Is that a handaxe in your pocket or are you just glad to see me?)

Friday is science day on this blog (sometimes) and it is most certainly Science day, ie, the day that my favorite scientific journal is published. As we often do, my partner on the human evolution beat, Ann Gibbons, and I have weighed in with the latest news about what hominids were doing and when. Ann's online story, about some 1.5 million year old Homo erectus footprints discovered in Kenya, has also received a lot of play in the general news media (thanks in large part to the efforts of our public relations department.) As Ann reports:

... a team led by Matthew Bennett of Bournemouth University in the United Kingdom scanned and digitized at least four trails of footprints laid down over several thousand years at Ileret. The researchers were able to use the size, spacing, and depth of the impressions to estimate the weight, stride length, and gait of the ancient walkers. As the researchers report in tomorrow's issue of Science, the new footprints show that these early humans were pushing off the ground with their big toes--or toeing off--and shifting their weight over these digits in the same way as modern humans. H. erectus's feet had clearly evolved a modern shape, with the big toe parallel to the other toes and a pronounced arch, says paleoanthroologist Brian Richmond of George Washington University in Washington, D.C.

Read the rest at the link, which is free for 4 weeks from today.

Meanwhile, yours truly has been looking into what some call the "sexy handaxe theory." As I explain in a Random Sample in today's issue of Science (subscription required):

Did prehistoric lasses make passes at lads with hand axes? In 1999, scholars proposed that the tear-drop shaped, often beautifully symmetrical axes produced by early humans were more than just tools. Rather, suggested Steven Mithen of the University of Reading in the United Kingdom and science writer Marek Kohn in a paper in the journal Antiquity, the best hand axes were the product of Darwinian sexual selection: a signal to gals that their makers had good, or at least handy, genes.

Now, two anthropologists writing online this month in PaleoAnthropology argue against sexual selection. April Nowell of the University of Victoria in Canada and Melanie Lee Chang of the University of Oregon, Eugene, call the hypothesis "evocative and romantic." But they say that the evidence for it doesn't hold up: For example, Mithen and Kohn argued that the axes' symmetry did not make them better tools, but Nowell and Chang cite several studies concluding that symmetry made the tools easier to control. The women also suggest that even early human females would have been seeking qualities in their mates--such as "niceness" and compatibility--more lasting than a well-turned hand ax. Kohn insists that he and Mithen aren't suggesting that female choice was "frivolous or superficial" but was based on how males performed difficult tasks.

Whoops, there I've gone and given you the entire text, so hope my editors will see this as a nice teaser for you to subscribe to the journal and not haul me off to copyright court. But in another free feature, on our Origins blog I also explore whether or not handaxes were really what most archaeologists think they are--a tool used for cutting plants or butchering animals--or if, as Australian archaeologist Iain Davidson has argued, they are what was left over when early humans struck off flakes, which were the real tools.

Complicated today, complicated in prehistory--that's us humans!

More about stone tools. An undergraduate archaeology student and expert knapper describes the mental and physical processes he goes through while making a hand axe, on the Origins blog. Fully illustrated!

Bonus blog: Why didn't Darwin discover Mendel's laws?


Anne Gilbert said...

You have to wonder sometimes about these handaxes. I've seen pictures of some that seem to be unusually well-made, as if the makers took a lot of time and effort to get that teardrop shape. There are, as you probably are aware, some examples of handaxes that have fossil shells embedded in them, more or less in the middle. I realize that Iain Davidson doesn't think these handaxes were used for anything at all, but were "leftovers" from flaking, but while this is an interesting argument from someone who seems to be rather dismissive of any suggestion that any kind of "esthetic sense" might have been developing before the emergence of "modern" humans, I don't think that what evidence there is backs this up at all. I don't know what handaxes may or may not have been used for. But (a)even if they were originally cores left from flaking, somebody saw that they could, themselves, have been used and (b), later ones, at least, are so esthetically pleasing that I, at least, have an inkling that whoever made these, tended, at the very least, to take a lot of pride in their work and the results of that work.
Anne G

terryt said...

"if ... they are what was left over when early humans struck off flakes, which were the real tools".

Doen't really make sense. Why would the bit left always be the same shape, if only roughly? Of course that doesn't eliminate the possibility that many were basically ornaments. In pre-European Maori society jade was fashioned into clubs but it's doubtful if most of them were used as such. Similarly shaped clubs of whale bone or stone were definitely used for the obvious purpose. Jade clubs were mainly hierlooms.

Seems there's a concerted effort being made to exaggerate the periodic changes in human morphology, culture and technology.

Michael Balter said...

While Davidson's idea is not widely accepted, it is plausible. If you held a stone core in your hand and took flakes off of one end, keeping the other end firmly wedged in your palm, it would take on a tear-drop shape. But the later handaxes do appear to have been deliberately shaped, while the earlier ones are more crudely made and could have fit Davidson's model.