February 22, 2024

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Genes Link High Reproduction to Shorter Lifespan: UK Biobank Study

Genes Link High Reproduction to Shorter Lifespan: UK Biobank Study

Genes Link High Reproduction to Shorter Lifespan: UK Biobank Study

Research Finds Genetic Variations That Promote More Reproductive Behavior Also Shorten Lifespan.

An analysis of genomic and behavioral data from the extensive UK Biobank has ultimately demonstrated that genes promoting reproductive behavior come at the ultimate cost.

Aging is undoubtedly painful. It leaves traces on your skin, slows down your movements, makes you forgetful, and everything hurts. Your joints crack and pop. Evolution has achieved so many remarkable feats; how can we still endure aging?

The Antagonistic Pleiotropy Hypothesis suggests that as you age, your body collapses to pay the price for the strong reproductive capabilities you had when young.

If the same gene has different roles at different stages of life (known as pleiotropy)—if it enhances your reproductive chances when you are young but somehow has harmful effects as you age—then this gene will still undergo positive selection and remain in the population because reproduction is so crucial.

Genes Link High Reproduction to Shorter Lifespan: UK Biobank Study

This idea is intriguing and has some anecdotal evidence, but it’s challenging to conclusively prove genetically, especially since reproductive traits and lifespan are largely influenced by environmental factors, lifestyle choices, and genetics. However, the UK Biobank makes this proof possible.

The UK Biobank holds complete genomic data for 500,000 UK volunteers aged between 40 and 70. These genomes are cross-referenced with individuals’ blood pressure, heart rate, grip strength, bone density, arterial stiffness, vision, height, weight, hip and waist circumference, workplace, education level, employment and medical history, diet and exercise habits, smoking and drinking status, among other information. Volunteers were recruited from 2006 to 2010, and data collection continued until 2016. Researchers worldwide have access to this information.

One of the researchers, Zhang Jianzhi, states on his lab’s website that they are “most interested in the relative roles of contingency and necessity in evolution.” Using the UK Biobank data, he attempted to answer the following questions: Are genetic variations influencing reproduction more likely to affect lifespan than randomness would predict? If so, is this association antagonistic? Are variations that promote both reproduction and aging favored by natural selection? The answers are affirmative, affirmative, affirmative.

Reproductive fitness doesn’t just mean having more children. To assess it, researchers also studied genes associated with reproductive activities, such as age at first childbirth (oddly, only for females), age of first sexual intercourse, as well as age of menarche and menopause. Since most people in the UK Biobank are still alive, researchers tested the genetic correlation of these factors with the lifespan of their parents. As they knew how many siblings each participant had, they could also look for correlations between parents’ reproductive abilities and lifespan.

Most genetic loci mediating the correlation between high reproductive rates and short lifespan are located in non-coding regions of the genome. This means they don’t alter the proteins the genes produce; instead, they change the time and cell type in which these proteins are made. For example, one genetic variation is linked to a younger age of first sexual intercourse and an increased risk of later melanoma and lung cancer.

These genetic factors run counter to environmental influences. Since the mid-20th century, environmental influences have led to a decline in birth rates, while life expectancy has increased. The authors point out that the extended lifespan is partly the reason they found evidence of antagonistic pleiotropy in the genomic data.

Therefore, the stronger the reproductive ability, the shorter the lifespan. It’s not because your children will drive you crazy and spend all your money, although they might very well do that. It’s simply the cost of having children.

Reference: “Science Advances,” 2023. DOI: 10.1126/sciadv.adh4990

Genes Link High Reproduction to Shorter Lifespan: UK Biobank Study

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