If I understand correctly, you’re saying that prehistorical hunter-gatherers avoided the Malthusian equilibrium by practicing a collective strategy of restraint from excessive breeding. But even if such a situation came to pass, it could never be a stable equilibrium over long periods of time. In such a situation, individuals who “cheated” by breeding above average and passing the same characteristic to their offspring would have caused their descendants to spread like wildfire, completely overwhelming those who restrained their breeding.
There is a general principle operating here akin to the old saying that nature abhors vacuum—namely, any population of reproducible organisms abhors a state where additional resources exist that could support further population growth all up to the Malthusian limit.
In such a situation, individuals who “cheated” by breeding above average and passing the same characteristic to their offspring would have caused their descendants to spread like wildfire, completely overwhelming those who restrained their breeding.
What simple adaptation do you propose to allow individuals to improve their average number of offspring, given that breastfeeding duration and menstruation-onset are traits of present-day foraging societies?
Or, for that matter, how do you explain the observed low population growth? Human fossils from that era don’t show signs of chronic malnutrition, and present-day foraging societies generally don’t have problems acquiring food.
There is a general principle operating here akin to the old saying that nature abhors vacuum—namely, any population of reproducible organisms abhors a state where additional resources exist that could support further population growth all up to the Malthusian limit.
This principle ignores the necessity of a mechanism for highly-variable population growth. Absent radical environmental changes (e.g. agriculture), such a mechanism has not been demonstrated.
What simple adaptation do you propose to allow individuals to improve their average number of offspring, given that breastfeeding duration and menstruation-onset are traits of present-day foraging societies?
Anything that makes people more phyloprogenitive will do the trick. In the long run, even behavioral mutations are conceivable, but cultural changes can also have a dramatic effect, and they act nearly instantaneously on evolutionary timescales. You yourself provide one possible answer: in the situation you describe, a mere cultural change that would shorten the breastfeeding period would, ceteris paribus, boost the fertility significantly.
Or, for that matter, how do you explain the observed low population growth? Human fossils from that era don’t show signs of chronic malnutrition, and present-day foraging societies generally don’t have problems acquiring food.
Obviously, the most reasonable explanation for low population growth is that the foragers were in a Malthusian equilibrium. The Malthusian principle says only that some resource constraint will stop further population growth, not what exactly that constraint will be. Other commenters in this thread have already suggested scenarios that wouldn’t necessarily leave too many emaciated corpses around.
The facts that early human populations: (1) expanded over vast continents, and (2) recovered from population bottleneck disasters imply that the potential for population growth was there, as far as the biological constraints on fertility are concerned. If local population growth wasn’t happening through prolonged periods of time, it means that something was preventing it. The idea that it was stopped by humans somehow successfully coordinating to limit their fertility and avoid the tragedy of the commons strikes me as implausible to the point of absurdity, for the reasons already mentioned. There is no plausible way how such a state of affairs could have emerged, and even if it did, it could never be stable through any significant period of time.
If local population growth wasn’t happening through prolonged periods of time, it means that something was preventing it. The idea that it was stopped by humans somehow successfully coordinating to limit their fertility and avoid the tragedy of the commons strikes me as implausible to the point of absurdity, for the reasons already mentioned.
I wholeheartedly agree.
Anything that makes people more phyloprogenitive will do the trick. In the long run, even behavioral mutations are conceivable, but cultural changes can also have a dramatic effect, and they act nearly instantaneously on evolutionary timescales. You yourself provide one possible answer: in the situation you describe, a mere cultural change that would shorten the breastfeeding period would, ceteris paribus, boost the fertility significantly.
Errr, yes, this happened. Approximately 10,000 years ago, in fact. Agriculture is a mere cultural change that shortened the breastfeeding period with a nearly instantaneous effect, by an evolutionary timescale.
The Malthusian principle says only that some resource constraint will stop further population growth, not what exactly that constraint will be.
Predation is not a resource constraint, yet it too halts population growth. The high rates of infant and maternal mortality that prevailed in all human societies prior to the past two centuries also limited population growth. Resource constraints, food or otherwise, are far from the sole determinant of population size.
If I understand correctly, you’re saying that prehistorical hunter-gatherers avoided the Malthusian equilibrium by practicing a collective strategy of restraint from excessive breeding. But even if such a situation came to pass, it could never be a stable equilibrium over long periods of time. In such a situation, individuals who “cheated” by breeding above average and passing the same characteristic to their offspring would have caused their descendants to spread like wildfire, completely overwhelming those who restrained their breeding.
There is a general principle operating here akin to the old saying that nature abhors vacuum—namely, any population of reproducible organisms abhors a state where additional resources exist that could support further population growth all up to the Malthusian limit.
What simple adaptation do you propose to allow individuals to improve their average number of offspring, given that breastfeeding duration and menstruation-onset are traits of present-day foraging societies?
Or, for that matter, how do you explain the observed low population growth? Human fossils from that era don’t show signs of chronic malnutrition, and present-day foraging societies generally don’t have problems acquiring food.
This principle ignores the necessity of a mechanism for highly-variable population growth. Absent radical environmental changes (e.g. agriculture), such a mechanism has not been demonstrated.
WrongBot:
Anything that makes people more phyloprogenitive will do the trick. In the long run, even behavioral mutations are conceivable, but cultural changes can also have a dramatic effect, and they act nearly instantaneously on evolutionary timescales. You yourself provide one possible answer: in the situation you describe, a mere cultural change that would shorten the breastfeeding period would, ceteris paribus, boost the fertility significantly.
Obviously, the most reasonable explanation for low population growth is that the foragers were in a Malthusian equilibrium. The Malthusian principle says only that some resource constraint will stop further population growth, not what exactly that constraint will be. Other commenters in this thread have already suggested scenarios that wouldn’t necessarily leave too many emaciated corpses around.
The facts that early human populations: (1) expanded over vast continents, and (2) recovered from population bottleneck disasters imply that the potential for population growth was there, as far as the biological constraints on fertility are concerned. If local population growth wasn’t happening through prolonged periods of time, it means that something was preventing it. The idea that it was stopped by humans somehow successfully coordinating to limit their fertility and avoid the tragedy of the commons strikes me as implausible to the point of absurdity, for the reasons already mentioned. There is no plausible way how such a state of affairs could have emerged, and even if it did, it could never be stable through any significant period of time.
I wholeheartedly agree.
Errr, yes, this happened. Approximately 10,000 years ago, in fact. Agriculture is a mere cultural change that shortened the breastfeeding period with a nearly instantaneous effect, by an evolutionary timescale.
Predation is not a resource constraint, yet it too halts population growth. The high rates of infant and maternal mortality that prevailed in all human societies prior to the past two centuries also limited population growth. Resource constraints, food or otherwise, are far from the sole determinant of population size.