One of the intriguing things about reading science articles over the years from various sources designed for an eclectic audience, both in terms of interests and levels of science education, is sometimes one gets to put together new and old information and make a left turn, if you will.
For many years the main source for reading about science in my world was Discover Magazine. (Scientific American had gotten too expensive and required too much educational background.) It has a wide range of topics - fields if you will - and articles range from paragraphs to several pages. Occasionally something sticks with me for years, then comes back from another angle.
These days those other angles can be PBS sources like "Nova" and "Nature", or other TV network offerings like the Blue Planet series. Of course there are all other kinds of cross connections out there. Some stand out. Others don't, or perhaps a detail does but its source is mislaid in my mental map. I'm pretty sure I can connect what I just read with a much older source, well over a decade back. Both just caught my attention and for the same basic reason: I'm a dog lover.
Today's source is my current favorite "brain food", Science X Newsletter. I get it online on weekdays. All kinds of things pop up on there, and I can easily spend two or three hours a day with it. (It's why I'm getting behind on TV!) The following is the introductory paragraph which caused me to read the full article:
"Simulation shows wolves had time to self-domesticate and evolve into dogs A team of mathematicians and statisticians from the University of Wisconsin-La Crosse, the University of Tennessee and Valparaiso University, all in the U.S., has found new evidence that wolves had ample time to self-domesticate and evolve into modern dogs. In their study published in the journal Proceedings of the Royal Society B, the group developed a computer simulation showing the evolution process."
What caught my eye was their conclusions were based on a supposed time frame of 15,000 years for the process to take place. I had to wonder if that was based on assumptions going into the study, or looking at the more practical work of actually breeding for selected traits leading to domestication. Yes, it says computers, but what was the input? GIGO? Does it assume absolutely no input from humans, even though it suggests the presence of humans are why wolves changed on their own?
My questioning is because I had read years earlier of domestication changes happening with purposefully breeding foxes, which if memory serves correctly was written about in Discover Magazine. My Way Back Machine is rusted so I can't pin it down more than that. The sheer novelty of domesticating foxes stuck all those years. The method used was picking from each new generation the kit(s) with the most baby-like features - for foxes - for breeding the next generation. Pointy features, like muzzles and ears, were selected against, so noses shortened and rounded, ears flopped. Friendlier behaviors were also part of the mix selected for. Succeeding generations quite shortly had evolved into versions of foxes suitable for domestic pets, as different from their ancestors as dogs from wolves. It didn't take very many generations for the change, as I recall, and certainly nothing remotely like 15,000 years. This was one person's project.
Of course, the difference raises questions about how wolves really were domesticated into dogs. Did they self-domesticate, or how strong was the hand of humans in bringing about the change? Was it a combination? Did it really take 15,000 year? Or maybe 15 generations? Is there an intrinsic difference between the two species that allows change in one to happen way faster than in the other? Did those looking at wolf evolution ever hear about the fox breeding results?
* * * *
How about totally different species? We know, for example, that there were woolly mammoths and mastodons in North America when humans were first known to be here. While our arrival date is debated and currently stretching farther back than first believed, it's not disputed that we hunted them in groups, for food at least, likely using other parts in other ways because we're clever that way. Just not clever enough to avoid making them extinct. We recently discovered an "elephant graveyard" of fossils of earlier relatives in northern Florida predating humans by a very long time. (Lucky them?)
Let's head to the other side of the globe, where two kinds of elephants remain. The smaller one is commonly domesticated. Has anybody asked when and how that happened? For example, was the now domesticated variety formerly larger? Wilder? Did long ago humans have a hand in shaping them? Are we still?
Look at horses. How much of their differences are evolutionary differences and how much are because clever ancestors found different needs/wants from them and bred for those, the same as we do today, sometimes with the result of over-breeding race horses to the point where legs no longer reliably survive racing?
We know we can do it, have done it, forcing adaptions on wild animals changing them to be "ours". Just how far has it spread?
No comments:
Post a Comment