Wild turtles age slowly, and some basically don’t age at all
futurity.org
futurity.org
Massive snakes like anacondas, reticulated pythons and such are partly arboreal when small. When bigger, they can't really climb or hide in trees. Same thing for giant monitors. Komodo dragons are arboreal when small, and live a different lifestyle once large. They're kind of like different species, inhabiting different ecological niches.
If iteration was important, sexual maturity would occur drastically younger in birds and mammals, and you'd have tons of offspring to maximize iteration. Reptiles are the ones that have tons of children.
>If iteration was important, sexual maturity would occur drastically younger in birds and mammals, and you'd have tons of offspring to maximize iteration
There are always antagonist selective pressures, e.g. selective pressures towards longer childhoods and fewer offspring when parental investment requirements grow.
This assumes there is some sort of reasoning going on in natural selection. What would lead to mutations that promote aging being selection per se, when the effects of aging are only experienced after reproductive age? That's not ruling out that mutations that cause aging aren't selected for, but they should give some short-term advantage.
“It sounds dramatic to say that they don’t age at all, but basically their likelihood of dying does not change with age once they’re past reproduction,” says Reinke."
In humans, kids are born well below the age when we see the worst effects of aging. The old do not play much of a role in natural selection. It seems likely that aging or lack of it is more of an accident, then.
Not that I've ever heard this theory before. But logically it seems plausible.
If you don't age and can stop growing at optimum size, then that's potentially a huge evolutionary advantage. And since even “marginally better” can often be selected given enough pressure, it's hard to imagine why growing older is so prevalent.
Although the ones that were big got extinct so maybe you have a point...
It's more likely that those animals descended from an ancestor that didn't 'age' in the conventional sense _and_ had slow, unrestricted growth. Those two traits are not necessarily related.
Not sure if I agree with the 'specialized' moniker. All creatures are specialized to their ecological niche. Humans are kind of an exception.
What may have been selected for is fast and adaptable organisms. Why bother with 'aging' if you can tolerate damage over time, in exchange for more efficient organisms in the short term? You only need to repair enough to ensure the organism will reproduce (and maybe help care for the offspring for a while).
Humans are actually pretty good in that aspect compared to many animals. Probably because it takes a while before we are able to reproduce.
Random mutations can easily cause problems/chop some time off your lifespan.
The question is, do individuals within the species benefit from longer life spans? To what extant are age related problems contributors to the deaths of individuals within a species?
I would guess that a higher percentage of turtles at a reproductive age die of age related disease than reproductively mature rats. I would guess that turtles are much better at withstanding the passage of time, because time is a much more significant killer of turtles.
Similarly, flying birds and bats tend to live longer than mammals of similar body mass, probably because predation is a less significant contributor to their mortality (and thus issues such as age, relatively more significant). Primates may be an exception, but they're also rather good at avoiding predators.
Anyway we're close to retiring and I suppose it will transition to my daughter eventually. Maybe it will outlive her too.
The turtle's terrarium (a big aquarium tank) is parallel to my path to the office, so I also know it's hungry, aside from the banging, when it sees me coming and races me the length of the tank. Did I mention that it appears to differentiate between me and other people?
[1] A favorite story I like to retell (and Grandpa starts in with...) is when our daughter was oh 11ish and we had a bunch of her classmates over I liked to drop a big tomato hornworm into the turtle tank with the kids all gathered round. When the cabal got packed in tight and a bunch of eeewwws! started I knew that once again, it was nature, green in tooth and claw.
The thinking is that these protective mechanisms can reduce mortality rate (you're not getting eaten by others), so you're likely to live longer, which exerts pressure to age more slowly.
Biggest support for the protective phenotype hypothesis is in turtles.
Also, how do these species with extremely long lifespan adapt to changing environment?
Reptiles do not need another reptile's blood
Below is an example of a random insight:
> His article Cholesterol in Context states that aging “seems to be a state of cholesterol starvation.” In other words, the ability to make cholesterol diminishes as we age.
https://www.womensinternational.com/blog/aging-is-cholestero...
It's tough to synthesize his thought though. Whoever does and sells a popular level book of it will make a lot of money.
Sorry, couldn't miss a factorial joke.
Saying that your chance of dying is 50% after 80 != saying it's the same consistently after 80?
(that is, chance of flipping tails 10 times in a row is 0.5¹⁰ - chance of any head is what's left)
It's calculating P(death|age = N), not P(death|age <= N). Now luckily you can calculate the second one, by adding all values up to that age together.
I would argue the value you're looking for, "when you die", is different still: P(death|age <= N, current_age=M), where M is your current age. You know, taking into account that you didn't die from sudden infant death syndrome or measles, or you wouldn't be here, but leaving everything in the future up to chance. To get that value, you should the odds of dying at all ages up to N, but only starting at your current age.
I think the observation they're trying to convey is that your expected number of years remaining goes down by much less than one year per year at those ages. A 90-year-old can expect to live for another 4.5 years, but on their 91st birthday, the chart surprisingly predicts not 3.5 but 4.2 years remaining. The number of expected years left drops more than 0.95 years per year until age 20, 0.9 years per year until age 40, down to 0.8 at 60, 0.5 at 80, and 0.1 at 100.
To have an average of 4.5, you need people to die before and after the mark.
So a lot of people drop off between 91 and 92. But those who make it to 92 have about 4.2 years remaining.
If you have a population of 100 people and 50 of them will live less than 1 year, and 50 of them will live an average of 10 years, that's 5.5 years on average for the whole population. But if you check that same population one year later, you will have 50 people who all live 9 years on average. You've managed to increase the average by eliminating the bottom.
Same thing is happening here.
And it's probably similar to professional sports careers. The average NFL career is about 3 years. However, if you make to 3 years, your average career length is about 7 years.
We probably need more of a median or mode than a mean.
The set of people alive at age N has size Sn. Some of them die. Some survive and form a new set of people alive at age N+1 with size Sn+1. Sn+1 <= Sn.
If the expected number of remaining years at age N was Y, death removed all the people that actually lived only 1 year or less, so the expected number of remaining years for people of age N+1 must be greater than Y.
Life expectancy at birth is always lower than at any other age.
Check https://en.wikipedia.org/wiki/Demography_of_the_Roman_Empire
> When the high infant mortality rate is factored in (life expectancy at birth) inhabitants of the Roman Empire had a life expectancy at birth of about 22–33 years
> The 46-49% that survived to their mid-teens could, on average, expect to reach around 48–54
No, that is neither necessary nor true. It must be greater than Y-1, not Y. Your way would mean that the expected duration of a life was infinite.
But this is a necessary fact about everything. The alternative would be that the expected complete lifespan of an 81-year-old would be less than the expected complete lifespan of an 80-year-old, and that forms a logical contradiction with the fact that, in order to achieve that longer lifespan, the 80-year-old must become an 81-year-old.
Annual chance of dying is 5% at 80 and continues rising every year (9% by 85, 16% by 90, 25% by 95, 35% by 100).
“The Gompertz–Makeham law states that the human death rate is the sum of an age-dependent component (the Gompertz function, named after Benjamin Gompertz), which increases exponentially with age and an age-independent component (the Makeham term, named after William Makeham). In a protected environment where external causes of death are rare (laboratory conditions, low mortality countries, etc.), the age-independent mortality component is often negligible. In this case the formula simplifies to a Gompertz law of mortality. In 1825, Benjamin Gompertz proposed an exponential increase in death rates with age.
The Gompertz–Makeham law of mortality describes the age dynamics of human mortality rather accurately in the age window from about 30 to 80 years of age.
You probably remembered the first part of the sentence following that:
“At more advanced ages, some studies have found that death rates increase more slowly – a phenomenon known as the late-life mortality deceleration – but more recent studies disagree.”
Even if that were true (something wikipedia contests. See also https://en.wikipedia.org/wiki/Late-life_mortality_decelerati...), that doesn’t mean rate of death decreases, just that it increases slower than this model predicts.
At a certain point, humans appear to stop aging. Just it is at 105, not 80 :)
Worth following on Twitter if you're into the topic: https://twitter.com/statto
Essentially, a brief summary of the book is that research is ongoing, there is some hope, but do not expect any treatment in the very near future, meanwhile eat healthy and exercise. Overall, it is a very good book for understanding the process of aging. Delves into scientific evidence and provides good description of the most recent developments. However, do not expect it to give you any valuable practical advice apart from you already probably know: you need eat healthy, do not smoke, exercise etc.
Your time is limited, so don’t waste it living someone else’s life. Don’t be trapped by dogma — which is living with the results of other people’s thinking. Don’t let the noise of others’ opinions drown out your own inner voice. And most important, have the courage to follow your heart and intuition. They somehow already know what you truly want to become. Everything else is secondary"
People (mostly) don't change - they (have to) die for change to happen. I'm considering myself to be modern - today. In 70 years I'm quite sure I will no longer be by a large margin and I highly doubt that I'll be able to adapt my thinking incorporating them - just as I observe my parents and their peers not to be fully able to do so. As humanity with this we have a pool of new approaches (young) and tons of experience (older) which maximizes the likelyhood of finding the right approach to new challenges & making us survive as a species
Measures of willingness to change your mind and ability to learn new concepts is correlated with age. It seems just as reasonable to argue that if we could solve aging, we'd solve stagnation.
Evolution's primary mechanism is to promote traits that increase the likelihood that you'll survive until you can reproduce. Perhaps multiple times. And for some species an additional period to raise the new generation.
So if evolution selects for a hard protective shell, this increases the odds that you reach reproductive age, which is the goal. This may accidentally also add an additional 100 years of lifespan. Which does nothing for reproduction, but it just happens anyway.
Quite a few examples in nature where species drop dead directly after mating.
How much of that is a consequence of the fact that our brains physiologically lose the ability to change over time though?
An excellent justification for the forced retirement at 65 years of faculty in universities in East Asia. The sclerotic atmosphere in most US research universities, where over-privileged professors often linger into their 80s, has in my lifetime led to a growing intellectual stagnation in many (most? all?) academic fields.
Take any period in human history before 10,000 years ago and you'd find that nothing ever happened. As old person, the world would look exactly the same as when you were young. Even in modern times, there's centuries with no progress at all.
Oh wait, I did try a turtle egg at a bar one time in a shot of chili guaro... Don't bite them open, there's sand inside.
At no point was there any reference to particular inherent qualities of turtle meat, that I recall.
I'm not a picky eater by any means but there's definitely some meats out there I see on the menu and don't order, octopus for example - They're too smart to be munching on.
edit: hell, birds are pretty smart, too, even if domestic chickens seem exceptionally stupid.
That is certainly the first time I have heard this said about turtles.
Probably geosmin[1]. Some people really dislike it, others don't seem to mind as much. I grew up eating catfish and crawfish so I don't mind my food tasting a little muddy or ditchy, but that's just me.
I wouldn't call 190 years old "trivially older".