Elephant Brain Soup

A little while back I was talking about a recent paper that allegedly debunks the expensive tissue hypothesis (ETH). Another recent paper by Miki Ben-Dor et al does just the opposite, specifically in regard to human encephalization and dietary animal fat. And not just any animal fat, ELEPHANT FAT! Paul Jaminet mentioned the paper back in December in a positive light, and everyone's favorite paleo apostate Don Matesz talks about the paper in a much more negative fashion, not surprisingly.

Man the hunter of elephants, are we awesome or what? Sorry, I mean allegedly awesome. And actually it wasn't we homo sapiens but pre-we homo erectus (childish snigger) that would've been doing the alleged hunting.

The elephant in question is the now extinct Elephas antiquus which roamed Europe and the Levant up until about 115,000 (Wikipedia) or 400,000 years ago (Ben-Dor et al and references for the Levant) when the coming ice age and predation by humans led to its demise. Now there's plenty of evidence that elephants were hunted by humans (or pre-humans depending on your definition), even up in perfidious Albion:

The elephant, which has been identified as a straight-tusked Palaeoloxodon antiquus, would have been twice the size of the largest modern African elephant.

The skeleton was also found with a number of flint tools surrounding it, indicating that it was probably slaughtered by humans. 

Hold on there BBC. Twice the size of the largest modern African elephant? That sounds a little off to me. To quote Wikipedia: "The largest individual [African elephant] recorded stood four metres (13 ft) to the shoulders and weighed ten tonnes." Wikipedia gives Elephas antiquus a height of 3.90 m (12 ft). Are you saying the elephant fossil found in Kent was 8 m (26 ft) tall? I'm rather skeptical. I think the largest elephant that ever existed was Mammuthus sungari, and it was just over 5 meters tall. Have I ever mentioned how much I hate lazy mainstream science journalists?

Anyway, getting back to the Ben-Dor et al paper. Here's the abstract:

The worldwide association of H. erectus with elephants is well documented and so is the preference of humans for fat as a source of energy. We show that rather than a matter of preference, H. erectus in the Levant was dependent on both elephants and fat for his survival. The disappearance of elephants from the Levant some 400 kyr ago coincides with the appearance of a new and innovative local cultural complex – the Levantine Acheulo-Yabrudian and, as is evident from teeth recently found in the Acheulo-Yabrudian 400-200 kyr site of Qesem Cave, the replacement of H. erectus by a new hominin. We employ a bio-energetic model to present a hypothesis that the disappearance of the elephants, which created a need to hunt an increased number of smaller and faster animals while maintaining an adequate fat content in the diet, was the evolutionary drive behind the emergence of the lighter, more agile, and cognitively capable hominins. Qesem Cave thus provides a rare opportunity to study the mechanisms that underlie the emergence of our post-erectus ancestors, the fat hunters.

They are essentially arguing that it was the pressure of reduced opportunities for easy pickings like a few tons of elephant steak, that led to the changes we see between elephant gorging pre H. saps (whatever you want to call them, the taxonomy is contentious but I'll stick to H. erectus because it is way funnier than H. heidelbergensis) and the less muscular, longer-limbed and bigger-brained H. saps.

By looking at gut-size, the ability to process protein (via liver and kidney capacity), brain size and overall body weight, Ben-Dor et al came up with these tables.

So H. saps had an allegedly reduced overall energy requirement and body weight despite their increased brain size. Ever wonder why it's so hard to pack on muscle despite all that time spent in the gym? Blame your lazy ass ancestors for wiping out the elephants.

Once we got addicted to these walking supermarkets by having larger brains and especially larger daily energy expenditures (DEE) we then proceeded to exterminate them. Oops. Time to buckle down. Ben-Dor et al argue that the next step was to reduce overall DEE while increasing encephalization in order to take advantage of smaller, fleeter game such as antelopes and aurochs.

Now I'm not going to lie to you, as a paleo-ish person I see this as an extremely sexy hypothesis. But I'm also a huge contrarian. So I'm going to offer up a few counter-arguments.

To me, real hypotheses are all about making predictions and having them tested. This is why I hate string hypothesis, predict something, motherfuckers, and we'll test it, otherwise you got nothing.

What I find think is interesting about the Navarette et al paper is that they used a testable hypothesis to predict something which they then used to disprove the original hypothesis. I love that. I'm skeptical of the assumptions they used, but I love the methodology. The Devil is in the details, especially when it comes to experimental science, but it all rests on the back of predictive hypotheses.

So a problem I see with the paper from Miki Ben-Dor who has a blog entitled Paleo Style, or with archeology in general it is pretty easy to cherry-pick or insert one's biases, because it's all in retrospect and the data is so scant.

With that contrarian bitching aside, I think it's a pretty interesting paper.