Is modern man a "wimp"?

That’s the conclusion of a Reuters article, which describes a book by Australian science writer Peter McAllister. The book is titled, Manthropology: The Science of the Inadequate Modern Male.

At some level, there’s no denying that Nature doesn’t make men like she used to. As I detailed in Slate last spring, our skeletal muscles have half the strength of chimpanzee muscles, holding their mass constant. Neandertals were comparatively stocky and muscular – especially compared to their mass – leaving modern human hunter-gatherers in the dust.

But Neandertals weren’t built like modern-day weightlifters. So I’m always skeptical when I see direct comparisons of ancient and modern people. The changes aren’t always in the direction you might assume.

McAllister’s bottom line is perfectly accurate:

"The human body is very plastic and it responds to stress. We have lost 40 percent of the shafts of our long bones because we have much less of a muscular load placed upon them these days. "We are simply not exposed to the same loads or challenges that people were in the ancient past and even in the recent past so our bodies haven't developed. Even the level of training that we do, our elite athletes, doesn't come close to replicating that.

Not all the skeletal changes in recent populations have been caused by plasticity; there are some good reasons to think that our recent gracility is a product of evolutionary change. But it is entirely true that our bone cross-sectional areas have greatly reduced, with consequent reductions in compressive and torsional strength. We don’t suffer the stresses of the past, and our bones are weaker than ancient peoples’ – at least in comparison to our mass.

That’s the complicated part of any comparison – men in Westernized nations today tend to be bigger than many ancient groups of people. If you’re going to compare “wimpiness” between Neandertals and living men, you have to understand the relative masses.

Let’s take McAllister’s example of a hypothetical body-building Neandertal woman:

McAllister said a Neanderthal woman had 10 percent more muscle bulk than modern European man. Trained to capacity she would have reached 90 percent of Schwarzenegger's bulk at his peak in the 1970s. "But because of the quirk of her physiology, with a much shorter lower arm, she would slam him to the table without a problem," he said.

The shorter lower arm is clearly true – Neandertals had short arms, and particularly short lower arms. But today’s women have short lower arms compared to men, and they don’t routinely win arm-wrestling contests. It does come down mostly to muscle.

Did Neandertal women really have 10 percent more muscle bulk than modern European men? At 60-80 kg in mass, Neandertal women were between the 5th and 50th percentiles for American white men (link). Neandertals were leaner than American men today, but females are not as lean as males. Women today have a muscle mass between 15 and 25 kg; men between 20 and 40 kg. Conceivably, a Neandertal woman would have been comparable to today’s men in terms of muscle mass, but I don’t see an obvious basis for the idea that Neandertal women were 10 percent more muscle-bound than men today.

What about speed?

His conclusions about the speed of Australian aboriginals 20,000 years ago are based on a set of footprints, preserved in a fossilized claypan lake bed, of six men chasing prey. An analysis of the footsteps of one of the men, dubbed T8, shows he reached speeds of 37 kph on a soft, muddy lake edge. Bolt, by comparison, reached a top speed of 42 kph during his then world 100 meters record of 9.69 seconds at last year's Beijing Olympics. In an interview in the English university town of Cambridge where he was temporarily resident, McAllister said that, with modern training, spiked shoes and rubberized tracks, aboriginal hunters might have reached speeds of 45 kph.

Usain Bolt’s 10m split times in the 2008 Olympic 100m race are posted here. The top speed of just over 42 kilometers per hour corresponds to a 10m split of 0.82 seconds.

A speed of 37 kph would correspond to a 10m split of 0.97 seconds. If the ancient Australian ran the same 100m race profile as Usain Bolt, with split times based on the proportion 0.97/0.82 compared to Bolt’s, the 100m time would be 11.46 seconds, compared to Bolt’s 9.69.

The Wisconsin high school track record 100m time is 11.84 seconds. For girls. The boys’ record is 10.27 seconds.

Now I’m not saying that 37 kph isn’t an impressive speed – there’s no way I could run that fast, even if I were being chased by a Sasquatch. My point is just that there isn’t very much time separating a good high school athlete from the World Record. Sprinters spend an intense effort training to shave a miniscule fraction off their times.

Maybe it’s true that modern shoes and a good training regimen could have made this ancient Australian into a Bolt-beater. Several aboriginal Australians have become world-class track athletes. Running with bare feet on natural substrates is tough – although some modern track athletes have preferred to train that way.

But it’s hardly a knock against “modern males” to say that ancient footprints would have crossed the finish line a second slower than the fastest Wisconsin boys.

Anyway, the article notes a few more anecdotes from the book. On the whole, it sounds like the book has some interesting stories. McAllister may be on safer ground with many of his ancient historical cases – the marvelous endurance of Athenian rowers and Roman legionnaires, for example. The main idea is the recent decline in skeletal robusticity, which is well documented.