Of Course Pregnancy Is At The Limit Of Human Endurance – That’s How Evolution Works

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An interesting finding about the link between endurance athletes and pregnancy. Which is that we can work out about how good endurance athletes can get by looking at the extreme to which the human body can be subjected and still – long term – survive. The finding being presented as a bit of a surprise, that this is about the limit to which pregnancy subjects the body.

Well, yes, obviously, that’s how evolution works:

The Tour de France is one of the world’s most gruelling events. Over 23 torturous days, competitors will cover more than 2,100 lung-bursting miles. They will train for years in the hope of clinching a coveted yellow jersey. Yet when it comes down to pure endurance, research suggests another group easily outperforms these elite cyclists: pregnant women. A review of some of the world’s most physically demanding pastimes suggests that even the most impressive human specimens will hit a ceiling that determines how long they can sustain their activity. Rather than lung-capacity or hours spent training in the gym, the human body’s ability to extract energy from food appears to be the limiting factor.

Yep, OK. Something is going to be the limit to the system. With that cycling directly it tends to be the ability to suck in oxygen and get it into the bloodstream. Although there’s a nice little extra. Top end cyclists eat vast amounts, yes. But they also have a distressing tendency to smother everything in ketchup. That precise mixture of sugar and vinegar and salt etc being something that aids in digestion. It gets those calories through the gut wall that little bit faster. But longer term it is, well, can you keep yourself fed doing that much exercise?

Obviously, it’s possible to do something stupid like a marathon which uses up, in a day, more than a day’s possible intake of calories. But you can’t continue using up stored energy forever. So, sustainable:

The ultimate limit of human endurance has been calculated by scientists who found that pregnant women are close to the maximum.

Well, yes, obviously. That’s the way evolution works. So, we’re mammals, development takes place inside the womb as much as is possible. Humans are born pretty early given that head size/pelvis constraint. But think what would happen if the whole process were not near the limit?

Those born from mothers not going to he limit would be less developed, smaller, less strong, weaker immune systems, something or other, than those whose mothers had gone closer to that limit of what is possible to aid in that development. The weaker would be outcompeted over the generations by those stronger. And yes, there would be an arms race, the limit being, well, that limit. Those investing more energy in the pregnancy than could be sustained wouldn’t be having children at all because they’d be dead.

So, given just how evolution works we’d expect to be where we are. Pregnancy will be at about the limit of sustainable human effort. Just because that’s how it all works.