carnap wrote: ↑Mon Mar 19, 2018 7:27 pm
Something that clearly causes some specific disease or set of diseases that noticeably reduces life-span. At the moment there is no reason to believe that meat consumption, as a whole, causes cancer or heart-disease.
What's "clearly causes"? We're talking increased risks here, but there's every reason to believe the links are causal.
There is very strong mechanistic evidence, in addition to good epidemiological evidence (despite the noise) for some kinds of meat (red meats pretty clearly causes colon cancer, for example).
Harvard has a brief overview here:
https://www.health.harvard.edu/newsletter_article/red-meat-and-colon-cancer
When it comes to fish, there appears to be a U shaped relationship with mortality, and it may be true that a modest amount of fish is more protective than harmful due to the DHA (although no reason to believe that algal DHA wouldn't be just as good or better for a vegan).
There are many reasons to believe that most animal products are harmful in any significant amounts, but that's kind of irrelevant to the point at hand which is your misuse of evolutionary biology to imply that they should not be.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pmOn the contrary, heart disease can start to develop in early adulthood.
It can, but significant effects are rare, particularly when we're dealing with a population that is neither obese nor sedentary.
I wouldn't consider it a "great devil" in early adulthood or childhood. It's unlikely to kill anybody before 40.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pmI'm not misusing evolutionary biology because I disagree with your claim, a claim that you haven't provided any evidence for.
You made the claim that evolution tells us something about this: you're the one who needs to provide evidence for all of the necessary assumptions that would need to be made for that to be true. I don't think conjecture counts as evidence.
It perhaps being plausible that some evolutionary account involves pressures for adaptation to meat's effect in the elderly is not the same as it being demonstrated to be probable that such an account is true.
You can't say "The Earth is flat" and then when I reply "No, it's an oblate spheroid" go on to suggest that I need to provide evidence for my counter-assertion, and explain in detail how your ad hoc hypothesis works, but in terms of evidence providing only crumbs that support the plausibility of *part* of the model.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pmNot at all and I never suggested such a thing, what I suggested is that it would be surprising if meat had profound negative impacts on our health.
It would be surprising if the kinds and amounts of meat that we ate during our evolution had profound effects on our health before or during our reproductive peaks that reliably prevented reproduction, particularly with physical activity.
Nothing outside that is necessarily surprising, and if you want to assert that it is you need to provide some good evidence for why that would be.
More modest effects (which may be below the level of being a "devil") are not so surprising, because it could easily be that they DID have such effects because it's functionally impossible to evolve resistance to them (again, you need to show that it's even possible; examples in animals seem to suggest that it is not possible), but that the nourishment they provided (which is not needed now) more than made up for them.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pmRight and I provided evidence in a previous post, the study I cited looked at teeth and found plenty of older samples. But the samples were more common in the upper paleolithic period.
You mean this?
http://www.nytimes.com/2013/03/24/magazine/who-lives-longest.html?_r=0
Rachel Caspari, a paleoanthropologist at Central Michigan University, studies the life spans of ancient humans, their ancestors and close relatives — together, known as hominins. In 2004, she and a colleague examined teeth from 768 hominin fossils representing three million years of primate evolution.
Looking at wear and other signs of aging in the teeth, Caspari split the fossils into groups of old and young adults, creating rough approximations of ancient demographics. Examing a span from between 100,000 and 30,000 years ago, Caspari found about four old adults for every 10 young adults. But beginning around 30,000 years ago, during the Upper Paleolithic, this reversed: Caspari counted 20 old adults for every 10 young adults.
1. 768 fossils over three million years is probably not a good sample; what portion of those were actually upper paleolithic? And what did she have to compare them with? And what kind of biases affected corpse preservation, or which she had access to?
2. Old and young groups? Worst. Granularity. Ever.
3. Regardless of any of that, tooth wear is not a good sign of ageing without dietary and food preparation controls. Wear is
highly influenced by environment, particularly moving into an era where food preparation with stone tools was likely more common.
If I can find the actual study later, I'll look it over, but this is pretty weak.
Even if you accept this as credible evidence for what you're claiming (and I see no indication it should even indicate the lifespans you're suggesting), this is a much shorter time period with much more advanced technology (including fishing), not much longer than how long we've been farming compared to the whole 200,000 years of modern Homo Sapiens.
It's also one with wildly variable cultural practices.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pmI also pointed to research on hunter-gathers, these groups have similar lifestyles to our paleolithic ancestors and around 20~30% of the people in a given population are over 60 which.
1. What research did you "point to"? Did you forget to post a link? I looked back and still can't find anything. There were a couple other brief comments in that Times article, but nothing short of cherry picking to fit the narrative.
Popular work on tribal societies is rife with factual errors and bad methodology:
http://quillette.com/2017/12/16/romanticizing-hunter-gatherer/
If you have a link to an actual study, please post it.
2. Even if you don't think the problems with the research you're paraphrasing completely discredit it, 30% should be an obvious red flag; that indicates a baby-boom a little over 60 years prior, and likely lower fertility since then or an incident that increased infant mortality or killed off a number of adults, not a stable demographic. Japan has those kinds of numbers and they have a serious problem. It's obviously an outlier, not representative of life expectancy (for that you need a real demographic study).
3. Even if that were true (which I do not believe it is), there's no good reason to think their lifestyles are very similar. There are huge technological and cultural differences today, as well as environmental ones and humanitarian aid and rule of law provided by neighboring states. It's a ridiculous comparison.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pm
You still seem to be misconstruing the term "life-expectancy", its an average.
I meant to say lifespan.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pmIt doesn't make sense to talk about a "maximum".
It makes sense to talk about the oldest examples we have observed; it's a very important data point when we have few other objective metrics to look at.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pmAnd there is nothing dramatic about claim, you'd find it any textbook on primatology.
Which is an incredibly ignorant comparison given the serious confounding variables.
You can't claim that chimps should regularly reach their potentials in captivity with the same medical care, and ignore the captivity part. We also have significantly less ability to treat and monitor chimpanzees due to poor feedback and difficult behavior, even if the budget and knowledge were there to provide them the same level of care.
Some people just assume that our long lifespans today are as natural as those short lifespans commonly observed in chimps. This is NOT an assumption that should be made.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pmThe life-span of chimpanzees is around 45~50, gorillas around 35~40 and so on. Human life-span is around 80.
You're just begging the question, and assuming the very conclusion you want to arrive at.
Chimps, Gorillas, and Humans are by no means living in equally "natural" environments that they evolved in.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pmAgain life-span isn't a claim about how long a given animal can expect to life, that is life-expectancy. Its a statement about how the animal ages.
Which is something you're assuming by ignoring confounding variables.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pmThe oldest living samples (which I think is what you mean by maximum life-expectancy) of chimpanzees and humans are roughly consistent with the life-spans are cited. The oldest chimpanzees are in their late 60's, oldest gorillas in their late 50's and oldest humans in their early 120's.
No they aren't. You're correct about humans, but not Chimps.
https://www.cnn.com/2012/04/21/us/oldest-chimpanzee-in-captivity/index.html
"Little Mamma" in that article, 74
https://www.palmbeachpost.com/news/local/new-little-mama-oldest-living-chimp-dies-lion-country-safari/16zwQ1k0ixvwmCqTdyip8K/
She died a few months ago, last November. She should have been around 79.
Around 80 vs. 120.
Not that dramatic a difference. Again, about 1.5 times, as I said. Which is about the same difference as the ratio for sexual maturity (8 years old vs 12 years old).
If we had larger populations of captive chimps to observe (as we have huge populations of humans to draw from) we'd no doubt have even older examples. Do you deny this?
You're trying to compare apples to oranges here, since the population samples we have create such a bias (and they're also in captivity).
Medical care is one thing that should increase life expectancy (and there's no reason to believe it's the same for veterinary care for reasons I mentioned and others I didn't), but captivity decreases it.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pm
All apes mature slowly, chimpanzees enter adulthood at around 13 years where as humans its more around 16~18 years. So the slower maturation in humans doesn't even come close to explaining the longer life-span.
What the hell are you talking about? It explains it perfectly well.
Your arbitrary "entering adulthood" numbers maybe not as much (FYI, humans don't reach full maturity until the 20s, if you want to stretch chimp maturity out that far), but something more objective like sexual maturity maps to the differences we've seen for maximum lifespans.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pmbrimstoneSalad wrote: ↑Mon Mar 19, 2018 5:32 pm
It doesn't make sense for an animal to regularly outlive fertility; when this occurs, cycle length should increase so it's a slower burn.
You're right it doesn't make sense which is why the human case is surprising, the
life-span of human women is much longer than their fertility and that is really curious.
Again, you are begging the question.
You are just assuming natural human lifespan (during the bulk of our evolution) WAS longer than fertility.
There is no reason to believe that.
The better explanation is that the age of menopause tells us what our natural lifespans were during the bulk of our evolution, and that longer lifespans today are happenstance of environment making it possible to live longer than we would have combined with a lucky side effect of slow maturity that evolved for completely unrelated reasons.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pmYou're speaking like there is no issue here and this is just an issue I'm pulling out of my ass, yet its been a curiosity to anthropologists for some time:
https://www.ncbi.nlm.nih.gov/pubmed/11223885
I'm sure there have, but again they're just assuming menopause evolved for some important reason. There's no reason to assume that.
The simpler explanation is that we just did not usually live that long historically, which would be in line with most other species.
Even if we did live that long due to some happenstance of environment combined with slower growth, fertility just may not have changed (rather than having evolved to actually lose fertility), either because it did not have time to change, or due to many other possible reasons which have nothing to do with the grandparent hypothesis.
For example, risk of Down Syndrome starts climbing exponentially after 40. Due to human empathy, the presence of these children may have just been harmful to the tribe as resource drains (of course infanticide is common in tribal societies, but that would have just made these children useless and created conflict for no reason); it does not necessarily have anything to do with grandparents being important so much as the offspring they're capable of producing being less likely to survive, and more likely to drag others down.
Even without that, the mere existence of these infertile grandparents could still be a drain on the tribe, but just not enough of one to evolve some kind of kill switch at 50 (if that's even possible to evolve). There's no reason to postulate that we evolved in order to live longer, since their existence at all (if we lived that long) is much more easily explained as a side-effect of slower human growth and maturity (very important for brain development), and their being tolerated and cared for despite being a drain is easily explained as a side effect of human empathy (very important for group cohesion and cooperation).
The grandparent hypothesis is a ridiculous narrativization of evolution. It's a nice story and people favor it due to the emotional appeal of everything having meaning (and who doesn't love old people? It just
FEELS true that they must be important), but it's a terrible ad hoc hypothesis with no credible evidence.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pm
Your comments here are conjecture that are based on the idea that there is some how a fixed amount of eggs or number of cycles an animal can have, but neither are accurate.
Conjecture?
OBVIOUSLY.
I'm not saying that they do, but given that we're closely related it's pretty plausible lacking other evidence that they are similar.
It's at least as credible as your arguments, probably more so because there are fewer needed assumptions. We don't even have to assume that we evolved to have a different number of eggs from our close relatives, which is reasonable.
My point is that arguments like these aren't that compelling. Evolution itself tells us very little.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pmWith evolutionary modeling you can test hypothesizes like this for plausibility and researchers have done just that, for example the study I just cited.
Plausibility in the sense of not clearly impossible? That it could be true? Maybe. But that gives us no indication of meaningful probability.
And you only get to the former by piling on some extra ad hoc hypotheses.
Don't get the result you want? Just add more assumptions until it works! That's science, kids!
I don't have a problem with people speculating on the reasons this or that evolved, it's mostly just an exercise in storytelling (evolutionary fan fiction) when we have a sample of ONE and no hard evidence, but it's harmless in itself.
What I have a problem with is people extrapolating from those unproved hypotheses and using them to come to conclusions and then pushing those conclusions as arguments in place of modern empirical evidence. I feel like that's what you've been doing.
In order for a violation of it to
surprise us, the hypothesis can not just be plausible in the sense that it's reasonably possible that it could be true for all we know because there might be a mechanism that could fit, it must be overwhelmingly probable that it's true.
It's not reasonable to come to any conclusions about any of this based on evolution. We should neither be surprised nor unsurprised about anything that turns up about meat and human health beyond a very limited period in adulthood and extreme outcomes that would preclude successful reproduction.
carnap wrote: ↑Mon Mar 19, 2018 7:27 pmYes, but human fertility starts to dramatically decline at around 35. Between 40~50 women are in a period of pre-menopause, they still have a cycle but its very difficult to get pregnant naturally. This is why women in this age group typically utilize various technologies to have children.
Yeah, not sure what this has to do with anything. It's hard to map human and chimp fertility carefully, I'm just using general numbers. Very likely chimpanzee fertility wanes later on as well.
carnap wrote: ↑Mon Mar 19, 2018 7:44 pm
Also a theme in your discussion is that diseases like heart-disease, cancer, diabetes, etc are only issues in old age but that is far from being the case.
Never said that, but when they're caused by environment they typically manifest later (particularly the issues with most animal product consumption).
carnap wrote: ↑Mon Mar 19, 2018 7:44 pmSo if some component of meat promoted cancer there would be clear selection pressure for any gene that provided protection.
Genetic resistance to cancers caused by dietary exposure and resistance to cancers that affect children are totally different.
carnap wrote: ↑Mon Mar 19, 2018 7:44 pmAs mentioned in my last post, heart-disease can start to develop in early adulthood and has a number of negative impacts on health before it becomes deadly (stroke activity, reduced blood flow, etc). Similar for type 2 diabetes, its a disease that progresses slowly over time and early stages have negative consequences.
I addressed this earlier. Are they "devils" at that point, in your view?
Modest effects could be compensated for by nutritional benefits, and would also be particularly rare given other risk reducing behavior like good BMI and high physical activity.