If a typical mammalian species survives for ~1 million years, should a 200,000 year old species expect another 800,000 years, or another million years?
tl;dr I think itās āanother million yearsā, or slightly longer, but Iām not sure.
How much of this future might we live to see? The fossil record provides some useful guidance. Mammalian species typically survive for around one million years before they go extinct; our close relative, Homo erectus, survived for almost two million.[38] If we think of one million years in terms of a single, eighty-year life, then today humanity would be in its adolescenceāsixteen years old, just coming into our power; just old enough to get ourselves into serious trouble.
(There are various extra details and caveats about these estimates in the footnotes.)
Ord also makes similar statements on the FLI Podcast, including the following:
If you think about the expected lifespan of humanity, a typical species lives for about a million years [I think Ord meant āmammalian speciesā]. Humanity is about 200,000 years old. We have something like 800,000 or a million or more years ahead of us if we play our cards right and we donāt lead to our own destruction. The analogy would be 20% of the way through our life[...]
I think this is a strong analogy from a poetic perspective. And I think that highlighting the typical speciesā lifespan is a good starting point for thinking about how long we might have left. (Although of course we could also draw on many other facts for that analysis, as Ord discusses in the book.)
But I also think that thereās a way in which the lifespan analogy might be a bit misleading. If a human is 70, we expect they have less time less to live than if a human is 20. But Iām not sure whether, if a species if 700,000 years old, we should expect that species to go extinct sooner than a species that is 200,000 years old will.
My guess would be that a ~1 million year lifespan for a typical mammalian species would translate into a roughly 1 in a million chance of extinction each year, which doesnāt rise or fall very much in a predictable way over most of the speciesā lifespan. Specific events, like changes in a climate or another species arriving/āevolving, could easily change the annual extinction rate. But Iām not aware of an analogy here to how ageing increases the annual risk of humans dying from various causes.
I would imagine that, even if a species has been around for almost or more than a million years, we should still perhaps expect a roughly 1 in a million chance of extinction each year. Or perhaps we should even expect them to have a somewhat lower annual chance of extinction, and thus a higher expected lifespan going forwards, based on how long theyāve survived so far?
(But Iām also not an expert on the relevant fieldsānot even certain what they would beāand I didnāt do extra research to inform this shortform comment.)
I donāt think that Ord actually intends to imply that speciesā ālifespansā work like humansā lifespans do. But the analogy does seem to imply it. And in the FLI interview, he does seem to briefly imply that, though of course there he was speaking off the cuff.
Iām also not sure how important this point is, given that humans are very atypical anyway. But I thought it was worth noting in a shortform comment, especially as I expect that, in the wake of The Precipice being great, statements along these lines may be quoted regularly over the coming months.
If a typical mammalian species survives for ~1 million years, should a 200,000 year old species expect another 800,000 years, or another million years?
tl;dr I think itās āanother million yearsā, or slightly longer, but Iām not sure.
In The Precipice, Toby Ord writes:
(There are various extra details and caveats about these estimates in the footnotes.)
Ord also makes similar statements on the FLI Podcast, including the following:
I think this is a strong analogy from a poetic perspective. And I think that highlighting the typical speciesā lifespan is a good starting point for thinking about how long we might have left. (Although of course we could also draw on many other facts for that analysis, as Ord discusses in the book.)
But I also think that thereās a way in which the lifespan analogy might be a bit misleading. If a human is 70, we expect they have less time less to live than if a human is 20. But Iām not sure whether, if a species if 700,000 years old, we should expect that species to go extinct sooner than a species that is 200,000 years old will.
My guess would be that a ~1 million year lifespan for a typical mammalian species would translate into a roughly 1 in a million chance of extinction each year, which doesnāt rise or fall very much in a predictable way over most of the speciesā lifespan. Specific events, like changes in a climate or another species arriving/āevolving, could easily change the annual extinction rate. But Iām not aware of an analogy here to how ageing increases the annual risk of humans dying from various causes.
I would imagine that, even if a species has been around for almost or more than a million years, we should still perhaps expect a roughly 1 in a million chance of extinction each year. Or perhaps we should even expect them to have a somewhat lower annual chance of extinction, and thus a higher expected lifespan going forwards, based on how long theyāve survived so far?
(But Iām also not an expert on the relevant fieldsānot even certain what they would beāand I didnāt do extra research to inform this shortform comment.)
I donāt think that Ord actually intends to imply that speciesā ālifespansā work like humansā lifespans do. But the analogy does seem to imply it. And in the FLI interview, he does seem to briefly imply that, though of course there he was speaking off the cuff.
Iām also not sure how important this point is, given that humans are very atypical anyway. But I thought it was worth noting in a shortform comment, especially as I expect that, in the wake of The Precipice being great, statements along these lines may be quoted regularly over the coming months.