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Why have humans no evolved anymore

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I am going to directly quote a book I have read because it gives a great answer:

Recent selection (evolution):
At the end of the Pleistocene, every continent (except Antarctica) was populated and each non-African population exhibited a subset of the common genetic variants found in Africa (Barbujani & Colonna, 2010; Campbell & Tishkoff, 2010; Henn, Cavalli-Sforza, & Feldman, 2012). See Figure 4.1. The now global human population exploded during the Holocene, almost certainly due to the transition to agriculture. This explosion generated the large number of rare variants noted earlier, most of which are of recent origin (5–10 kya) and more or less specific to the major continental populations. Thus, there has been recent genetic divergence among the continental populations, but much of this variation—perhaps 95%—is neutral or weakly deleterious (Fu et al., 2013; Fumagalli et al., 2011; Tennessen et al., 2012).
Regarding recent cognitive evolution, Huang et al. (2013) conducted a meta analysis of 27 studies of positive selection across the human genome and found that genes that are highly expressed in the central nervous system are enriched in recent positive selection. Keeping in mind that false positives are common in studies of positive selection, possible examples of divergent positive selection on neural function include: opioid cis-regulatory alleles (Rockman et al., 2005); loci involved in the axon guidance pathway, which determines the direction the axon will grow, ultimately influencing the development of neuronal networks (Tennessen & Akey, 2011); genes in non-African populations in the neuregulin ERBB4 signaling pathway, which is involved in the development of the nervous system, heart, and other tissues (Pickrell et al., 2009); selection of downstream gene targets of FOXP2, which is implicated in language abilities, in a European sample but not an East Asian or African sample (but the selected downstream genes have multiple functions in neural and nonneural tissue) (Ayub et al., 2013); and alleles in Ashkenazi Jews that have been argued to increase intelligence in heterzygotes but cause severe disease in homozygotes (Cochran & Harpending, 2009).

Additionally, population differences in frequencies of alleles impacting neural function might be due to founder effects and drift. Such seems to be the case with the dopamine D4 alleles (Kidd, Pakstis, & Yun, 2013).12 Finally, because exposure to neurotoxins from plants, fungi, pathogens, and the environment varied across populations, some divergent neural evolution might represent protective changes in neuroreceptors and other neural functions. Nevertheless, despite the lack of compelling evidence to date, it would not be surprising if there were limited population divergence in some neural/psychological functions due to recent positive selection on cognition and behavior.
Regarding recent cognitive evolution, Huang et al. (2013) conducted a meta analysis of 27 studies of positive selection across the human genome and found that genes that are highly expressed in the central nervous system are enriched in recent positive selection. Keeping in mind that false positives are common in studies of positive selection, possible examples of divergent positive selection on neural function include: opioid cis-regulatory alleles (Rockman et al., 2005); loci involved in the axon guidance pathway, which determines the direction the axon will grow, ultimately influencing the development of neuronal networks (Tennessen & Akey, 2011); genes in non-African populations in the neuregulin ERBB4 signaling pathway, which is involved in the development of the nervous system, heart, and other tissues (Pickrell et al., 2009); selection of downstream gene targets of FOXP2, which is implicated in language abilities, in a European sample but not an East Asian or African sample (but the selected downstream genes have multiple functions in neural and nonneural tissue) (Ayub et al., 2013); and alleles in Ashkenazi Jews that have been argued to increase intelligence in heterzygotes but cause severe disease in homozygotes (Cochran & Harpending, 2009).

Additionally, population differences in frequencies of alleles impacting neural function might be due to founder effects and drift. Such seems to be the case with the dopamine D4 alleles (Kidd, Pakstis, & Yun, 2013).12 Finally, because exposure to neurotoxins from plants, fungi, pathogens, and the environment varied across populations, some divergent neural evolution might represent protective changes in neuroreceptors and other neural functions. Nevertheless, despite the lack of compelling evidence to date, it would not be surprising if there were limited population divergence in some neural/psychological functions due to recent positive selection on cognition and behavior.

In short, in the past 10,000 years:
- Human population exploded rapidly.
- This resulted in many rare genes being mutated.
- Most mutations have not been beneficial.
- Most evolution in the past 10,000 years has been to do with optimizing brain function and emotional regulation.
- Europeans have evolved to more commonly display FOXP2 regulation of CNTNAP2 and RBFOX1 which alters speech development (can interact with other genes to increase odds of Autism in European populations).
- Ashkenazi Jews have evolved the GCH1 mutation that increases intelligence in hetero-zygotes but creates disease in homo-zygotes like Tay-Sachs.
- Neurotransmitters have become more stable through evolution.
- The development of sickle-cell Anemia in Africans (protects against mosquitos) and Lactase (ability to digest milk), notably (but not exclusively) in Europeans.

We are still evolving, though mainstream science scarcely acknowledges this due to the assumption that significant evolution takes hundreds of generations to produce marked effects.

More recently there has been buzz about the 'NOVA1' gene that is a unique human evolution, apparently it allowed us to develop more complex speech than Neanderthals. There is a pretty funny, recent study where they inserted the NOVA1 gene into mice and the mice got depressed.

 
Halloween, only 1 week away!
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- Ashkenazi Jews have evolved the GCH1 mutation that increases intelligence in hetero-zygotes but creates disease in homo-zygotes like Tay-Sachs.
Actually it is a mistake to say this 'mutated', it was already present (founder effect) and increased in frequency due to increases in population and endogamy.
 
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It's a lengthy process and evolution doesn't just happen, it's the slow accumulation of changes caused by the environment or mating preference or whatever

The modern human has already changed though. Look at the myopic rates in Korea now VS then.

That's a change brought by our lifestyle and that's a change that can be carried down via genetics.

We are in a really weird place right now
 
The Shadow one
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Feb 23, 2025
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It's a lengthy process and evolution doesn't just happen, it's the slow accumulation of changes caused by the environment or mating preference or whatever

The modern human has already changed though. Look at the myopic rates in Korea now VS then.

That's a change brought by our lifestyle and that's a change that can be carried down via genetics.

We are in a really weird place right now
iqmaxx, skinmaxx, facebonexxx, breeding maxx before the baby, and then pregnancymaxxing and pubertymaxxing for the son
 
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