Is Human Overpopulation Comparable to Invasive Species?

[Buzz Bloom]

The premise/model of food production seems particularly illogical to me. Since prior to modern times food production was labor intensive, food production tracked closely with the number of people available to produce food.

Hi russ:

I never read the original Malthus paper, so I may be incorrect in what I believe about it. I do believe that Malthus had another relvant concept besides food and the people to create it: the space in which food may be produced. This space was, and is finite, although there is more of it now then there was in the Malthus era. A lot of forests have become farms. Malthus failed to include the effect of forest destruction on climate change, which has its own impact on a future population collapse.

Regards,
Buzz

 

[BWV]

Came across this, which suggests that disease was the real check on population and was driven by density, not the availability of food.

Earth scientist Jed Kaplan and colleagues suggest that less than one-half of the land currently used for food production was used in 1600 and less than one-third in 100 CE. It is true that making more of the land available takes more work—sometimes brutally hard work, and that risks malnutrition. Again, some land couldn’t be cultivated without innovations, including heavy plows and irrigation. Nonetheless, it seems clear that throughout most of history the number of humans on Earth fluctuated far below the maximum possible.
Instead, we should probably thank (or blame) the regulatory mechanism of infection for limiting populations. As the number of people grew, population density drove up disease rates. This thinning mechanism was, in most places, probably the most powerful check on the number of people, particularly during the centuries that humans have been farmers. …And when infectious death declined in the nineteenth and twentieth centuries, population, urbanization, intensification, land use, and prosperity all climbed to historically unprecedented levels worldwide.

Although there’s a lot of interesting history in Kenny’s book, I’m not sure he does enough with this insight. To me it seems a fairly important finding that the foundation of modern technological civilization is the ability to control infectious disease. (To be fair to Malthus, he did discuss disease as one of the mechanisms that acted to limit human population growth, but he generally discounted its importance relative to food supply.) Modern economies are all fundamentally dense, urban economies–the US is 82% urban, China 60%–and this population structure cannot be sustained without a set of technologies and practices that manage infectious disease.

When industrialization and urbanization happened without those controls, as they did in early 19th-century Britain, they led to actual declines in living standards and life expectancy. Rampant disease in pre-industrial cities like ancient Rome killed off residents faster than they could reproduce, requiring a continuing inflow of migrants to maintain their population. If our current systems for controlling infectious disease weaken or fail, therefore, we’re in trouble

https://andrewbatson.com/2021/03/16/misunderstanding-malthus-mistake/

 

[Klystron]

{snip}
this will relate in later but have you ever seen a baby pidgeon ?
most people will say no
most baby pigeons hide and are never seen until adulthood
before humans said let's COLONIZE pidgeons lived in rocky cliffs.Pidgeons adjusted somewhat well and live in nooks and cranneys in cities {snip}

After reading this interesting thread again, I can answer your question for western USA.

As a casual birdwatcher I have often seen young pigeons once they grow feathers and learn to fly. Young pigeons appear almost identical to adult birds but noticeably smaller by comparison. I have seen youngsters, usually in the company of adults, learning which items to eat, avoid danger and how to interact with other pigeons in their flock.

After this stage I understand most pigeons form 'teen flocks' or social groups within the larger community while reaching mating maturity, making size comparisons with adults even more difficult. Pigeon hobbyists have specific names for each age group and can tell 'children' from adults by behavior as well as size.

AFAIK unless you explore nesting sites, you almost never see live baby birds of any kind in the wild before fledging. So, the statement about baby pigeons hiding in seclusion applies to almost any bird species. I have seen dead baby pigeons fallen from nests and captured by predators.

Like chickens from southeast Asia, pigeons from north Africa were introduced to America as a popular food source.