I wasn’t very clear about the phrase “adult lifespan”, which I was probably using incorrectly. What I had in mind was “average lifespan only counting individuals who survive to adulthood”, which I think is similar if not the same as what you had in mind.
Life expectancy at birth may vary a lot, but I think it’d be interesting to see some example numbers to get a sense of the diversity, similar to how you gave lots of other sample numbers for other metrics. I assume one could compute it from survivorship curves. (This is just a general point for future work that people might do. You’ve already gathered a huge amount of info here, and I don’t mean to request even more. :) )
A species that lives in a cool climate does not necessarily have an average experienced daily temperature that is less than a species in a warmer climate, except for really extreme cases
My comment was partly inspired by this quote from your piece: “Species from cool temperate regions tend to have longer life cycles with about one generation per year (e.g., Danks and Foottit 1989), as do species living in areas that have a dry season. But we note that for many of these species, variable environmental conditions determine how many generations there are per year, and in addition, the overwintering generation will have a longer lifespan than growing season generations.” I didn’t read the source articles, but I was guessing that when species have longer lifespans due to cold or dry conditions, they presumably have to slow down metabolically during those unfavorable periods. And metabolic slowdown presumably means that activity by the nervous system slows down too.
I tried Googling about that and stumbled on Huestis et al. (2012). The authors expected mosquitoes to reduce metabolic rate during aestivation like happens for insects during winter diapause, but resting metabolic rate was actually higher during the late dry season. “The high ambient temperatures during the Sahelian dry season may prevent or limit a reduction in metabolic rate even if it would be adaptive.”
Still, it does seem true that insects experiencing cooler temperatures typically slow down metabolism (with your point taken that one has to consider microclimatic temperature). So I guess my point here reduces to the previous point about how winter-diapausing insects (as well as those experiencing reduced temperatures even not in diapause) plausibly matter less per unit time, in proportion to the extent of slowdown (leaving room for lots of exceptions and diversity depending on the details).
Very interesting about warm-weather diapause and metabolic rate for mosquitoes. I’ll agree that during deep cold-weather diapause insects are reducing metabolic rate (goodness, but maybe not when REALLY cold??). A quick lit search turned up seasonally variable brain size and cognitive abilities in shrews (Lázaro et al. 2018)!
No idea how this relates to lived experience tho. Extending this argument, would you also claim that species with slower metabolism have less lived experience than those with faster metabolism (e.g., “less sentience and less hedonic experience per day”), because then comparing between species with different metabolic rates is going to be quite difficult. In fact I think it quite likely that those species with faster metabolic rates have different lived experience rates than species such as humans, e.g., Healy et al. 2013.
Healy, K., McNally, L., Ruxton, G. D., Cooper, N., & Jackson, A. L. (2013). Metabolic rate and body size are linked with perception of temporal information. Animal Behaviour, 86(4), 685-696. https://doi.org/10.1016/j.anbehav.2013.06.018
Lázaro, J., Hertel, M., LaPoint, S., Wikelski, M., Stiehler, M., & Dechmann, D. K. (2018). Cognitive skills of common shrews (Sorex araneus) vary with seasonal changes in skull size and brain mass. Journal of Experimental Biology, 221(2), jeb166595. https://jeb.biologists.org/content/jexbio/221/2/jeb166595.full.pdf
would you also claim that species with slower metabolism have less lived experience than those with faster metabolism
Yeah, as an initial hypothesis I would guess that faster brain metabolism often means that more total information processing is occurring, although this rule isn’t perfect because the amount of information processing per unit of energy used can vary. Also, the sentience or “amount of experience” of a brain needn’t be strictly proportional to information processing.
In 2016 I wrote some amateur speculations on this idea, citing the Healy et al. (2013) paper.
Thanks for the further insights. :)
I wasn’t very clear about the phrase “adult lifespan”, which I was probably using incorrectly. What I had in mind was “average lifespan only counting individuals who survive to adulthood”, which I think is similar if not the same as what you had in mind.
Life expectancy at birth may vary a lot, but I think it’d be interesting to see some example numbers to get a sense of the diversity, similar to how you gave lots of other sample numbers for other metrics. I assume one could compute it from survivorship curves. (This is just a general point for future work that people might do. You’ve already gathered a huge amount of info here, and I don’t mean to request even more. :) )
My comment was partly inspired by this quote from your piece: “Species from cool temperate regions tend to have longer life cycles with about one generation per year (e.g., Danks and Foottit 1989), as do species living in areas that have a dry season. But we note that for many of these species, variable environmental conditions determine how many generations there are per year, and in addition, the overwintering generation will have a longer lifespan than growing season generations.” I didn’t read the source articles, but I was guessing that when species have longer lifespans due to cold or dry conditions, they presumably have to slow down metabolically during those unfavorable periods. And metabolic slowdown presumably means that activity by the nervous system slows down too.
I tried Googling about that and stumbled on Huestis et al. (2012). The authors expected mosquitoes to reduce metabolic rate during aestivation like happens for insects during winter diapause, but resting metabolic rate was actually higher during the late dry season. “The high ambient temperatures during the Sahelian dry season may prevent or limit a reduction in metabolic rate even if it would be adaptive.”
Still, it does seem true that insects experiencing cooler temperatures typically slow down metabolism (with your point taken that one has to consider microclimatic temperature). So I guess my point here reduces to the previous point about how winter-diapausing insects (as well as those experiencing reduced temperatures even not in diapause) plausibly matter less per unit time, in proportion to the extent of slowdown (leaving room for lots of exceptions and diversity depending on the details).
Very interesting about warm-weather diapause and metabolic rate for mosquitoes. I’ll agree that during deep cold-weather diapause insects are reducing metabolic rate (goodness, but maybe not when REALLY cold??). A quick lit search turned up seasonally variable brain size and cognitive abilities in shrews (Lázaro et al. 2018)!
No idea how this relates to lived experience tho. Extending this argument, would you also claim that species with slower metabolism have less lived experience than those with faster metabolism (e.g., “less sentience and less hedonic experience per day”), because then comparing between species with different metabolic rates is going to be quite difficult. In fact I think it quite likely that those species with faster metabolic rates have different lived experience rates than species such as humans, e.g., Healy et al. 2013.
Healy, K., McNally, L., Ruxton, G. D., Cooper, N., & Jackson, A. L. (2013). Metabolic rate and body size are linked with perception of temporal information. Animal Behaviour, 86(4), 685-696. https://doi.org/10.1016/j.anbehav.2013.06.018
Lázaro, J., Hertel, M., LaPoint, S., Wikelski, M., Stiehler, M., & Dechmann, D. K. (2018). Cognitive skills of common shrews (Sorex araneus) vary with seasonal changes in skull size and brain mass. Journal of Experimental Biology, 221(2), jeb166595. https://jeb.biologists.org/content/jexbio/221/2/jeb166595.full.pdf
That shrew thing is fascinating!
Yeah, as an initial hypothesis I would guess that faster brain metabolism often means that more total information processing is occurring, although this rule isn’t perfect because the amount of information processing per unit of energy used can vary. Also, the sentience or “amount of experience” of a brain needn’t be strictly proportional to information processing.
In 2016 I wrote some amateur speculations on this idea, citing the Healy et al. (2013) paper.