How Farming Transformed Human Evolution: The Impact of Agriculture on Our Development

The comprehensive analysis of ancient genomes has revealed significant insights into human evolution over the last 10,000 years. This research indicates that various populations worldwide have experienced similar evolutionary changes, particularly following the introduction of agriculture.

“Similar traits and genes are being selected in diverse populations,” says Laura Colbran from the University of Pennsylvania.

Evolution happens when genetic variation becomes prevalent in a population—often because it confers an advantage. By comparing genomes, we can identify recent signs of human evolution.

Colbran notes that ancient DNA is exceptionally valuable for this research, stating, “Using ancient genomes allows us to witness genetic history directly, as opposed to relying solely on inferential methods.”

Much of the recent research has primarily focused on European genomes, but Colbran’s team leveraged an increasing collection of genomes from outside Europe, analyzing over 7,000 ancient and contemporary genomes. Ancient genomes mainly originate from the last 10,000 years, while modern genomes are derived from living populations.

The research team utilized ancient genomes to predict possible modern genetic profiles without evolutionary influence, highlighting differences known as selection signals. They identified 31 selection signals, many of which were shared among varied populations, likely due to the independent rise of agriculture around the same era globally.

For instance, less than 25% of ancient individuals possessed the FADS1 gene, which encodes an enzyme that aids in converting short-chain fatty acids (common in plants) into long-chain fatty acids (predominant in meats). Increased production of this enzyme is thought to benefit individuals who adopt a plant-heavy diet. Currently, over 75% of people in Europe, Japan, and northern China carry advantageous FADS1 variants. The strength of selection for this gene has remained stable over the last 300 generations in Europe while intensifying in East Asia over the last century.

The genes impacting the alcohol dehydrogenase 1B enzyme, encoded by ADH1B, have also been critically analyzed. Variants of ADH1B are prevalent in East Asia and are associated with quick alcohol metabolism, leading to symptoms like facial flushing. Colbran stated, “This showcases the strongest selection signal we’ve observed in East Asia,” suggesting that this variant was favored to curb excessive alcohol consumption.

Even though this variant was absent in ancient Europeans, strong selection signals related to the ADH1B enzyme were identified. Colbran emphasized the need for further investigation to discern the involved variants and their specific impacts, indicating a likely adaptation to evolving alcohol consumption patterns.

The research team also explored traits influenced by multiple genetic variations, such as waist-to-hip ratios, often correlated with fertility. Surprisingly, they found a robust selection process stabilizing women’s waist-to-hip ratios within certain limits. “This is intriguing as it suggests a stabilization of selection,” Colbran remarked, emphasizing that while waist-to-hip ratios can differ across various populations, the ideal measurement likely exists in a balanced range.

As noted by Alexander Gusev at Harvard University, this study is remarkable for its analysis of ancient DNA that has yet to be thoroughly examined. Gusev explained, “The authors found enriched variants being selected within one population compared to others, indicating parallel selection across populations, previously hypothesized but not empirically demonstrated.”

Yashin Souilumi, from the University of Adelaide, emphasized that their novel approach reveals regions of the genome newly identified as subject to selection, complementing previously known areas. “Their innovative method optimally utilizes the vast amounts of available ancient DNA,” Souilumi stated.

Colbran concluded that these findings are merely the initial discoveries. As more non-European genomes are sequenced, we will uncover even more evidence of recent human evolution.

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