# Evolution and Modern Medicine. **URL:** \ **Category:** Great Debates\ **Created:** [March 26, 2014, 2:35pm UTC](https://boards.straightdope.com/t/evolution-and-modern-medicine/684602 "2014-03-26T14:35:02Z")\ **Posts on this page:** 7\ **Page:** 3
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [March 31, 2014, 11:50pm UTC](https://boards.straightdope.com/t/evolution-and-modern-medicine/684602/41 "2014-03-31T23:50:26Z")
> [@Trinopus](#): > > Well, are all evolutionary studies done on a “genome-wide association study looking for specific genetic markers?” A lot of evolutionary science is done observationally, without such in-depth technology. Darwin did most of his work without access to genome-wide searches for genetic markers: he observed physical traits in pigeons, worms, and other animals. > > You’re right, of course, the science could be done this way, but it isn’t the only way. If all you want to do is show that sexual selection is happening right now, today, you could just do option one: measure the reproductive success of beautiful people vs nonbeautiful people. If you want to prove the more difficult proposition that sexual selection has been strong enough, for long enough, and consistently enough to be an actual force, you’d have to do option two, or something similar. As far as I know, the only way to prove past evolutionary pressure is to use population genetics as I mentioned. The GWAS is just to help you figure out which genes to look at. There are other ways of doing that. ---
**Author:** ![Trinopus](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Trinopus](https://boards.straightdope.com/u/Trinopus)\ **Post date:** [April 1, 2014, 2:26am UTC](https://boards.straightdope.com/t/evolution-and-modern-medicine/684602/42 "2014-04-01T02:26:20Z")
> [@Smeghead](#): > > . . . As far as I know, the only way to prove past evolutionary pressure is to use population genetics as I mentioned. . . . I’m completely unclear here. What was Darwin doing, then, given that he had no recourse to population genetics? ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [April 1, 2014, 2:32pm UTC](https://boards.straightdope.com/t/evolution-and-modern-medicine/684602/43 "2014-04-01T14:32:53Z")
> [@Trinopus](#): > > I don’t think I agree with this principle. > > However…it could apply to human beauty, as many illnesses are disfiguring and unlovely. [From here:](http://darwin200.christs.cam.ac.uk/pages/index.php?page_id=d4) > [@](#): > > Generally sexually selected traits either signal fitness directly, as their development depends on good health or a good diet, or indirectly when they signal the ability of the male to survive despite the large cost imposed by the fancy plumage or what have you. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [April 1, 2014, 5:42pm UTC](https://boards.straightdope.com/t/evolution-and-modern-medicine/684602/44 "2014-04-01T17:42:20Z")
> [@Trinopus](#): > > I’m completely unclear here. What was Darwin doing, then, given that he had no recourse to population genetics? There’s a difference between what Darwin did - proposing evolution by natural selection as the driving force for the changes and adaptations we see in the world around us - and what we’re talking about - proving that one specific trait in one specific organism is the result of one specific subtype of evolutionary pressure. ---
**Author:** ![Trinopus](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Trinopus](https://boards.straightdope.com/u/Trinopus)\ **Post date:** [April 1, 2014, 9:02pm UTC](https://boards.straightdope.com/t/evolution-and-modern-medicine/684602/45 "2014-04-01T21:02:23Z")
**bump** : very cool! This is something that either wasn’t covered in my old physical anthropology classes, or else I was asleep that day. Thank you! **Smeghead** : I don’t think I agree. Darwin looked at some very specific evolutionary “causes and effects.” He studied the beaks on finches and the plumage of pigeons, for instance, without access to genetic data – or even the knowledge of genes themselves. (What most amazes me about Darwin is that he was able to demonstrate the “granularity” of heritage, and to show that there had to be discrete “objects” that controlled heredity of physical traits, all simply from observing the transmission of traits over generations in animals. He was well on the way to a mathematical model of genes.) ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [April 2, 2014, 3:20am UTC](https://boards.straightdope.com/t/evolution-and-modern-medicine/684602/46 "2014-04-02T03:20:10Z")
> [@bump](#): > > Sure, sexual selection exists, but in nature, the traits that are typically sexually selected for are proxies for health, freedom from parasites, vigor, access to food, etc… > … > They’re not being selected for bigger tails genetically, but rather to be stronger, faster, smarter or luckier. > > That’s the fallacy that you’re suggesting is happening in people- that we’re being selected as a population to be better looking, and that’s just not the case because the pretty/ugly indicators just don’t actually indicate anything now that we’re civilized- just about everyone has adequate access to food, and the offspring of ugly people aren’t disadvantaged in any evolutionary way that would cause them to be less numerous or successful than pretty people’s offspring. I’m afraid you’re committing the much more common fallacy of assuming that humans (and possibly other species) know _why_ they do a particular behaviour, and are actively trying to get their genes to the next generation. But it’s not so. You don’t need to know why you prefer humans of a particular gender and appearance any more than your leg needs to know why it kicks when a small force is applied below the knee cap. Furthermore, humans have changed our environment much faster, for the most part, than evolution can keep up with. The classic example is food preferences. In our natural environment, it made sense to eat as much as we could so that we didn’t starve at times when food was scarce. And sugary foods were almost always good for us – it wasn’t really possible to eat too much sugar – so sugar tastes good to us. Fast forward to the modern world. Sadly, there is no meta-brain rewriting our instincts now that food is abundant. We have retained our instincts, and the result is obesity. So in terms of attraction, yes, for the most part in humans we find things like good skin or defined abs indicators of health and fitness the same as any other species (that’s not to say that I agree with **Trinopus** that humans are evolving to become better looking). ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [April 2, 2014, 3:44am UTC](https://boards.straightdope.com/t/evolution-and-modern-medicine/684602/47 "2014-04-02T03:44:04Z")
> [@Mijin](#): > > we find things like good skin or defined abs indicators of health and fitness the same as any other species My final line here could be taken as being inconsistent with what I was saying earlier. But I’m just using the same shorthand that many in the field do. I’m not saying a given individual looks at boobs, say, and thinks “that’s an indicator of femininity and fertility”. It _is_ an indicator and that’s why it’s been selected for, but the individual doesn’t need to know that. [Previous page](https://boards.straightdope.com/t/evolution-and-modern-medicine/684602.md?page=2)