字幕表 動画を再生する 英語字幕をプリント Sex is fun, right? But, what if it wasn't? Finding a partner, maintaining a long-term partnership and procreating at the right time is very difficult. Wouldn't it be better to just… make another me? Six years ago, biologists discovered the Mycocepurus smithii, a species of ant which are ALL female; they're asexual. The queen clones herself and if the eggs go unfertilized they'll all hatch female. Bonus, they then have a whole host of awesome new ants! Sexuality is a lot of work, while asexual reproduction is exceedingly efficient (if less fun), and sexual dimorphism, or splitting into a binary sex pair, limits the species… doesn't it? Why do we have sex? Aside from the pleasurable feelings associated with sex, lowering of stress, strengthening of romantic bonds and so on and so forth… why? Those things are evolution's way of GETTING US to HAVE sex. That's not what I mean. You could say, the WHY is easy, we have sex to reproduce; sex equals passing on genes and a promise of success! But that's STILL not what we're asking. Like, why, man? The Smithii doesn't get busy! She's ASEXUAL. She just… clones herself. BIOLOGICALLY speaking, WHY sex? The question "why we have sex at all," has plagued scientists for decades. Some basic theories from the 80s assume the genetic variety is beneficial and sex allows us to purge bad DNA. A book in the 90s invented The Red Queen hypothesis, named after the character from "Through the Looking Glass." This describes sexual evolution like a race. We're all evolving to combat other organisms' mutations, and by doing so, we stay in balance. Essentially, as parasites and predators evolve, the hosts and prey evolve to survive them, facilitating reproduction. Of course, having two sexes is pretty inefficient when you look at it this way. If I'm in a race to the death, I don't want to have to find a date for Saturday too! They call it the "cost" of men, because we don't necessarily NEED men, or do we? I'm biased here, but I hope we do. A new study in Nature Genetics claims to have a scientific way to look at this… sharing our genetic material makes us stronger and better able to fight disease. Using genetic material from the 1,000 Genomes Project, researchers compared genomes from Africans, Asians, Europeans, Canadians of French descent and found some parts of our DNA are rewritten more often than others, causing hot and cold spots of genetic mutation. When binary species like humans mate, they EACH release genetic material that can allow the building blocks of genes and chromosomes to combine and mutate beneficially. Some mutations help us, while others increase our risk of diseases. The rarely overwritten "coldspots," it turns out, is where bad mutations survive. Thanks to sex and these mutations, our genetic material "worsens, and then gets better," but eventually, bad DNA is overwritten. According to separate research by the 1,000 Genomes Project, each human offspring has 60 genetic mutations, or about one for every 100 million letters of DNA. Both asexual and sexual organisms mutate, but asexual organism mutations have to be SO GOOD that they overcome the wider population size, fitness, and mutation rate. It's less likely a single mutated clone will succeed in a colony, versus the constant trial-and-error of sexual organism. That doesn't mean sexuality is better, just another means of success. Bacteria aren't the only asexual animals, some reptiles, insects, and fish reproduce without males around; so binary sexuality isn't a hard and fast rule. Some even do BOTH! Sometimes it's a long and seductive one. *bad-ump cik!* Why we have sex at all is still a mystery, but this pulls back the curtain just a little. In the end, asexuality might be faster, but sexuality's DNA lottery has it's benefits too! You're going to comment on this, maybe you already have. Why do you think, BIOLOGICALLY, we're not asexual? Get down there and talk it out.
B2 中上級 なぜ私たちはセックスをするのか? (Why Do We Have Sex?) 1098 52 Cheng-Hong Liu に公開 2021 年 01 月 14 日 シェア シェア 保存 報告 動画の中の単語