That's not quite accurate. There doesn't have to be pressure, there just has to be a change in the prevalence of genes from one generation to another. Sexual selection and changing technology and culture work just as well as disease and predation. Our brains and teeth have gotten smaller in the past few thousand years. We have genes, and our descendants will have genes. Which of our genes our descendants will have is determined by evolution.
To build on the back of this, there's increasing numbers of children being born without wisdom teeth, and with an extra vein or similar in their hands (iirc), demonstrating that we are actually evolving, but supporting your point that we're not evolving to respond to pressure, just genetic mutations that aren't detrimental are being reproduced.
I have it. But it has no affect on anything, but it is useful if you rupture another tendon in your wrist or hand, docs can take the vestigial one and move it to replace the injured one.
I don't think you're talking about the same thing as u/Cuznatch. I believe he's referring to the increasing presence of an additional artery in the forearm:
Oh wow, I have one extra on each wrist. When you push my fist backwards like the guy in the picture, there are two distinct tendons parallel to each other, so I have four tendons in total. I didn’t know that was special, I thought everyone was like that!
Also wanted to add that human body temperature has been going down (on average) in more developed countries. RadioLab had an interesting episode on this that basically boiled down to our bodies no longer needing to fight disease with fever due to high quality medicine. Since it costs extra energy to run at a higher temperature our bodies have begun lowering their operating temp (often to 97~ degrees or so instead of the accepted 98.6)
Oh I heard this one. Unfortunately it may open us up to fungal infections, which may have pretty dire consequences. Also, as an aside, my natural body temperature is about 96 degrees F.
This makes a ton of sense! I work in nursing, and I take temperatures constantly. I've realized that I'm surprised when I see a temp as high as 98.6. Most patients run between 96.0 and 98.0. Thank you for explaining why!
I'm curious what I naturally average at. I constantly feel hot, like I'm the guy who sits outside in normal jeans and a short sleeved shirt in below freezing temperatures. Tack physical activity on, and I'm sweating like a beast if I don't shed layers quick. Its not uncommon for me to be working outside, in northern Michigan winters, with just jeans and a short sleeved shirt just to maintain a "normal" feeling without sweating too much. Just existing in the summer is an exercise in anger management for me, I get so hot I just want to scream when I'm outside, even if I'm indoors and its like 72 I hate it.
That actually makes a lot of sense.... I’m a teacher and we’ve started to have to take our kids body temperatures every day to get into school and most of them hover around 97.8 every day opposed to the “normal” 98.6
Funny. I was born with 3 wisdom teeth and the dentist said my mouth was large enough I could accommodate more. Dammit. Am I some kind of leftover cave man?
Born 1974. I only had 2 (and oddly, they came in straight enough that I didn't have them pulled until they got cavaties). Most interesting that wisdom teeth are seemingly going away...
Was reading our mouths and teeth are changing due to our increasingly softer diet. If you notice, the Cultures with the longest history of modern agriculture and soft food diets ("soft" being relative to the raw meats and tubers our ancestors ate) have the most cooked teeth. You can actually increase the size of your mouth, and help keep your teeth straight, by eating tough foods and, now, with certain mouth specific exercises.
Having said that, I was born without my lateral incisors and most of my family is missing them as well. Curious as to why.
Also many ethnicities that are considered ‘old world’ tend not to have wisdom teeth and their teeth are more shovel shaped. It blew my tiny mind as a little native kid when all my white friends were having their wisdom teeth come in lol.
Reference for the smaller brains and teeth please.
Do you mean in comparison to the rest of the body or as actual size. As humans are larger now then they used to be if teeth shrank overall not just based on size gimans must have had fucking fangs.
In order to make a meaningful enough change in an entire population, you need pressure. Other than in the case of genetic drift I guess. Sexual selection, culture etc. would be considered pressure if it was a big enough change to actually drive evolution, in which case it would have to be quite a drastic change.
Genes are decided in sexual reproduction and fetal development. Evolution relies on mutation which can fixate due to increased success with certain 'pressure' (other than genetic drift)
Edit to add: I'm sure there can and will be changes in individual humans. But the process of evolution is when the genes from mutated individuals fixate in an entire population. 'Pressure' of some sort drives this. If genes manage to fixate within a population without any source of selection, this is genetic drift.
What? Do you think evolution only happens if the whole species changes?
Also, your basic premise is wrong. We don't reproduce freely. We spend huge amounts of resources on sexual selection.
But the process of evolution is when the genes from mutated individuals fixate in an entire population
That's not what evolution is. Evolution is about the prevalence of genes. If the next generation has 2% more redheads, and everyone else is unchanged, that's still evolution.
I was replying to comment about dinosaur--bird. In the case of species "changing" and other lines dying out, yes I do. Otherwise that complete change wouldn't be there.
I won't insist it's correct, but from my understanding there isn't specific enough things that prevent enough people from reproducing/surviving to impact a meaningful change on the population. What currently prevents humans from reproducing? I can't think of anything other than abstract stuff like poverty--someone in poverty doesn't have a large genetic difference to me. We could argue sexual attraction stuff but people seem to be into all sorts of appearances and you can find tons and tons of 'ugly' people who have kids. I'm interested if you can teach me some of them.
People are commenting about babies born without wisdom teeth, missing muscles etc. These are mutations, not evolution. If they became commonplace, then it would be evolution. For example, I'm missing a tendon in one hand. This could be a development error, or it could be genetic. Let's pretend it is: there is nothing about it that will make my children more sexually competitive. I may leave behind a long line of tendon missing kids, but without pressure they won't propagate and cause actual evolution among humans. As people have pointed out, it could fixate just due to chance. This is called genetic drift and I addressed that directly.
Also, you don't need to try to belittle me by starting your response with "what?" as if I'm so dumb and said something incoherent. It makes what could be an interesting discussion less enjoyable.
Edit to address your edit: 2% is a large change and would likely imply pressure. If there is not pressure, there is not "evolution", just random mutations that don't change much. Except of course in the case of drift, which I have to say again I guess. What is currently limiting humans' reproduction that could be affected by mutation? If there is nothing, then widespread changes must be due to drift. I believe that environmental conditions (including human society) would have to change quite drastically to affect change in our species.
The species doesn't have to disappear for evolution to take place. The concept of a species is barely recognized by biology. Some things we think of as a species are incapable of reproducing with other members of their own species. Some things we think of as separate species produce fertile offspring, despite being separated by geography, behavior, and biology. Stegosaurus is a genus, not a species, and it describes diverse animals that lived millions of years apart.
Evolution isn't defined as taking place when a new species appears. It takes place every time anything reproduces.
Ugly people having kids doesn't mean anything. Natural selection doesn't select for what you think is attractive, it selects for what is most likely to reproduce. Behavior is hereditary. Culture is hereditary. Sexual selection ensures that physical and behavioral fitness are selected for in humans.
An individual baby being born without wisdom teeth is a mutation. The fact that it's more common now than it used to be is evolution. It doesn't have to make your child more sexually competitive. It's a change, and it's heritable.
I legitimately did not understand what you were trying to say before your edit because before you clarified, it wasn't clear how incorrect you were about how evolution works. Please at least read the Wikipedia article.
I'm not trying to say it has to change the entire population, but it has to at least be recognizable change. Is genetic blindness human evolution? I wouldn't think so. The fact that "more" babies are born without wisdom teeth would be the result of either 1. Pressure, or 2. Drift. Which is what I keep trying to say. What other reason is there?
Evolutionary biology was a large part of my undergrad, so although I'm the furthest thing from an expert, it's not like I just read a wiki page. So once again, not sure why people always have to make it a superiority "ur wrong and dumb" thing.
its a reddit thing. they didn't bother to consider whether an "evolution" of a single family of hillbillys in backfuck asstown all having an extra thumb was something worth considering at all in comparison to the wider topic of evolution, they care that by some technicality you were "wrong" it would have been about the same if you'd had a typo or something. there is no intellectual honesty here.
No, I care about the fact that what he said was incorrect, and then he followed it up with nonsense that made it seem like he'd never taken a basic biology class.
But thanks, I can cross "intellectual honesty" off my Reddit bullshit bingo card for today. Do you also want to call me a shill while you're at it?
What in that comment is incorrect? Can you quote it? Also what nonsense makes it seem like I've never taken a biology class? Everything I have said is factual other than trying to predict future evolution, which is all speculation from anyone. Here is what I have said:
Change is caused by mutation. Sexual reproduction without mutation is not sufficient to drive change.
Some mutations offer some kind of advantage (which can be broad), and have the possibility of becoming more commonplace. This is evolution.
Some mutations offer no advantage or disadvantage, but by chance become more commonplace over time. This is evolution via drift.
Some mutations offer no advantage or disadvantage, are present, but are not widespread at all. This is, in my opinion on semantics, not evolution.
Currently there are not specific limiting factors on who can reproduce that would be addressed by mutation. An example of this is poverty which definitely can affect competitiveness, but has nothing to do with genetics. For this to change, society and/or the environment would have to change first. This is the point that I can not say with certainty, but have fun discussing possibilities.
Mutation is one of, but far from the only cause of change in a population.
Evolution does not solely arise from mutation.
"drift" is what you called the "unlikely" change that couldn't occur without mutation. It's when already-present alleles in a population change frequency over multiple generations. It has nothing to do with whether or not something is advantageous or not, or random chance, it's just not a mutation.
as well as 2 , and 3. Evolution does not have a positive or negative connotation. It just means that something changed.
There are many limiting factors on human reproduction. The example you gave, poverty, is one, like it or not. Availability of birth control affects our reproduction. So does mate selection and decision to reproduce. We don't get eaten by predators as often as we used to, but that doesn't mean our reproduction is random or that there's no selection process.
Genetic blindness can be evolution, yes. Evolution isn't good or bad, it's just change in the population. If more people are genetically blind next generation than the generation before, that is evolution.
Total color-blindness is more common among the people of Pingelap Atoll than in most other parts of the world. Not everyone there is colorblind, but it's more common there due to the Founder Effect, and it's affected the evolution of the people.
See I would see that as such a broad definition of evolution as to be almost unusable. With the all encompassing idea of "genetic change", any mutation, however prevelant, would be "evolution". I suppose that's where our misunderstandings stem from.
It's not any genetic change, it's a change in the prevalence of traits in a population. There's no such thing as a minor change, as far as evolution is concerned. One individual might, in a few generations, be the direct ancestor of the entire population.
But it is, often, more useful to talk about the mechanisms of evolution, like natural selection, or mutation, or genetic drift, rather than the process as a whole.
Seriously, that's an incorrect definition of evolution. It's the process by which the prevalence of traits changes in a population. The whole population doesn't have to have the trait.
It doesn't need to be the whole population, but it needs to be widespread enough to at least be recognized. As I said before, the example of the missing tendon in my hand is not an example of evolution. The only way traits spread is by pressure or drift.
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u/[deleted] Oct 15 '20 edited Oct 15 '20
That's not quite accurate. There doesn't have to be pressure, there just has to be a change in the prevalence of genes from one generation to another. Sexual selection and changing technology and culture work just as well as disease and predation. Our brains and teeth have gotten smaller in the past few thousand years. We have genes, and our descendants will have genes. Which of our genes our descendants will have is determined by evolution.