Two Legs / Four Legs

Did you know that the gestation period of an elephant is 22 months? With a baby on the way, it makes you think about the development cycle of humans and other animals. It's strange how it relates to evolution, and it got me thinking.

I don't recall the name of the show, but years ago I watched a documentary about evolution and it had a segment that described evolution with a visual. They had a table with a tiered wooden pyramid. The landing at the top represented the ultimate evolved animal for a specific niche. The host showed with a little figurine on this model that some animals evolved in large steps, meaning that they traversed several steps at once. However, this made it difficult to reach the top because they tended to overstep and miss. Animal types that took small steps, however, took longer to get to the right spot, but once they were there, they didn't waver much.

With this in the back of my mind I was discussing with my wife how some when most animals are born, they can usually walk right away. But humans needed the longest period of time to gain the strength to do this, which I thought was weird. Lisa pointed out that four-legged animals have to be born able to walk pretty quickly whereas two-legged animals don't need to.

I wonder if that is because walking four-legged is so similar to crawling, I mused out loud. But my thinking was backwards.

No, Lisa said right away. Four-legged animals have to learn to walk right away because their parents can't carry them.

Oh, yeah. That makes sense. Duh! Man, she's smart. I both hate and love it when she's right. Humans care for and look after their young much longer than any other species.

But then that led to another line of thinking on my part. Doesn't it seem unfortunate that we as an evolving species lost the ability to learn to walk quickly some time after we gained the ability to walk upright. It seems like we traded one good ability for another and from a certain point-of-view that is bad.

Or perhaps my thinking is still backwards. Perhaps because we can walk two-legged and carry our young, our gestation period can be a lot shorter --shorter than 22 months at any rate.

Oh, and just in case anyone is wondering, I believe that evolution is true and this does not interfere with my being a christian. I don't see these as exclusive ideas. Trying to pit religion versus science is oversimplifying both.

More Information

• National Geographic - In the Womb
• Evolution and Christianity - Does Evolution Contradict Christianity?
• Evolution and Christian Faith: Reflections of an Evolutionary Biologist