Yes, I think going with the group was probably a bigger factor in a low-information environment. But there had to have been people who struck off over the mountain, or across the water, to see what was on the other side. Maybe those were younger people without families yet, but some would have been families or whole villages who were suffering a drought or a flood or a famine. We see that today. People make incredible journies - and many of them literally die on the way - just because their current situation is so bad that risking death is worth it. We live in a high-information environment today, so people have some idea of what Western Europe or the United States looks like, and what might await them there, before they decide to go.
But still, people crossed the Pacific in small boats and traveled from Asia to North America, in great enough numbers that they probably died in droves and still proliferated. And they settled down at almost every step of the way. There are places here in the Americas where whole civilizations have disappeared, but I would imagine that indigenous peoples from Alaska to Tierra del Fuego are all descendants of the people who crossed over from Asia, possibly as much as 24,000 years ago. A quick Google search says the
Zuni of New Mexico & Arizona may be the oldest existing indigenous group in North America, possibly going back 4,500 years. They may be direct descendants of the
Ancestral Puebloan peoples (who were themselves descendants of even older groups, who no longer exist).
As for who made the choices to migrate - in some cases, over large distances or over terrain that wasn't itself a place they could settle - I imagine there were leaders in each group who made those decisions, if the decision wasn't made collectively. One way or another, they did it.
I think it's broadly true that populations that settled down grew larger than populations that were nomadic. Maybe human settlements have to pass through some kind of crucible, and many of them failed. It's possible that, when looking at the sweep of history, settling down and establishing villages, towns, and cities was "high risk, high reward", and while whole civilizations ultimately failed and disappeared, maybe settling down was still the best bet for the development of human civilization. Of course, the individuals, families, and communities making these choices wouldn't have been looking 5,000 years down the road. They might not have been looking 50 years down the road. So in the moment there had to have been something that told them that farming the banks of this river here was the thing to do. Maybe their feet hurt and they didn't want to walk any more, and good enough was good enough, and hey, there's fish and ducks in this river, and hey, bison migrate right past here twice a year, and then -boom- fifty years go by and, what do you know, we have a village in the spot where somebody's grandparents decided to take a break because their feet hurt.
(It may be that one of the many unrealistic things about the Civilization games is that players get to choose where their Settlers found a new settlement.)
New climate science outlines the likeliest windows of migration along the 'kelp highway'
around.uoregon.edu
There are so many factors that can come into play, and it's hard to unpick which are significant, which bad decisions were avoidable, and which choices were really just good luck. Also, if the migrating people lacked some genetic traits they might not have been able to get far into new territory and survive.
I'll give an interesting example at the end of this post if you can stay awake!
Sedentary populations can be unlucky for reasons that would have been inexplicable to them at the time.
For example, if the soil is selenium deficient, the consequence will be that the fertility rate of women is lower. So one group of farms thrives and others not that far way do not.
In North America there are places that are terrific for raising cattle, but close by, there are areas with the same appearance, same vegetation, watered by the same streams that are terrible because the soil has a higher fluorine content and some livestock can get very ill from eating the grass there. For early settlers that would be inexplicable. Fluorosis is also a problem in some parts of India and China when people use deep wells for drinking water. Bad luck for them!
Even the presence or absence of Neanderthal genes in more modern populations would have had an effect on the farming communities that arose around Europe.
The presence of certain Neanderthal genes can be the cause of a greater proportion of premature births, but at the same time those same genes increase the chances of the prem baby and mother surviving. If the net effect is a higher survival rate then that will lead to population growth. Otherwise they can diminish and fail completely.
There are also combinations of Neanderthal genes that are beneficial against some diseases and detrimental in others.
Some recent findings are that the mortality rate from Covid (and likely other strains) is much higher in populations
with higher proportions, and very much lower in, for example, East Asians, who have almost no trace of Neanderthal genes. Bad luck for the early European communities exposed to corona viruses, irrelevant to the Asian ones.
Not relevant to early farming, but interesting IMO: a recent pharmocogenetic finding is that effectiveness of painkillers like ibuprofen is higher in people with (IIRC) three particular Neanderthal genes. WTH!
As you mentioned, there are some groups who went to extraordinary lengths to find places to settle and farm. One that fascinates me, because of work done by a colleague who died tragically a few years ago, are the Lapita people who were able to colonize Micronesia, New Zealand, Hawaii, and islands as remote as Easter Island and the Chatham islands.
A few quotes and factoids from:
Charles E.M. Pearce and Frances M. Pearce,
Oceanic Migration - Paths, Sequence, Timing and Range of Prehistoric Migration in the Pacific and Indian Oceans,
2010.
The Polynesian motif (the most familiar example would be actor, The Rock) is characterized by a tall body, a round head, a long thick trunk and short thick arms and legs and a large muscle-mass.
Anatomists are said to be able to recognize a Polynesian skeleton from uniquely large muscle attachments visible on the bones. The selection principles involved are, of course, a limiting of the body’s surface in relation to body mass to reduce loss of body heat and a maximizing of muscle mass to enable maximal capacity for exercise and for shivering, both of which generate body heat and are major protections against hypothermia.
Statistics based on factors such as stature/weight index and sitting to standing height index (ratio × 100), which are measures of a cold-adapted body type, suggest that New Zealand Maori are more cold-adapted than any other recorded cold climate group. Eskimos and Lapps have sitting to standing height indices of about 52.5, Maori has one of 53.8. The stature/weight index "ranges from under 2.6 for males from cold climate regions such as Finland, Iceland and England, through to values above 3.2 for Vietnam, Burma and India (Molnar, 1983). The Polynesian male values of between 2.22 and 2.39...are lower than that recorded from any cold-climate group".
How did a people who live on Halmahera, one of the Spice Islands on the equator, acquire an amazing resistance to famine and hypothermia?
Interestingly, they also have a relatively greater proportion of Denisovan genes than most other populations.
Did the presence of genes from cold-adapted, distant ancestors help them in their extraordinary migrations?
So many mad professors, so few Igors to do the lab work.
