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Arizona State University researchers have discovered that a genetic mutation linked to increased susceptibility to diseases like cardiovascular disease and Alzheimer’s, present in 20% of human populations, manages to persist through natural selection, despite having negative impact later in life. The mutation is related to Apolipoprotein-ε4 (APOE-ε4) which is an allele that is associated with enhanced fertility in women.

Alzheimer’s gene associated with increased fertility

Researchers partnered with the Tsimane community in Bolivia, known for their forager-horticultural lifestyle, to study the impact of APOE-ε4 gene variant from an evolutionary anthropology perspective. This collaboration utilized data from the long-standing Tsimane Health and Life History Project, which has collected demographic and biomedical information while delivering medical assistance over two decades. With 17,000 people across 90 villages, the Tsimane’s lifestyle, unaffected by urban modernization, provides a distinctive opportunity to investigate health and aging.

Lead study author Benjamin Trumble said that he tries to get insight on what human health was like prior to civilization. Trumble added that in the vast majority of human history, people existed as hunter-gatherers. However, the present world is markedly unusual—a constructed environment that starkly contrasts with evolutionary past. This places humans in a situation where they are functioning beyond the expected parameters of the original design.

In the research, Trumble and colleagues collected data from 795 Tsimane women aged 13 to 90. They examined genetic variants and fertility details like age of first birth, time between births, and total children born.

Women with single APOE-ε4 allele have more births

Researchers discovered that Tsimane women with a single APOE-ε4 allele had 0.5 more births, while those with two copies of the allele had an average increase of two live births compared to those without it.

According to Trumble Women with the APOE-ε4 allele reproduce nearly a year earlier and have shorter gaps between births, leading to the possibility of having half or even two additional children. The sudden increase in fertility could clarify the persistence of a mutation that leads to negative effects like cardiovascular disease or Alzheimer’s later in life.