AP Biology class blog for discussing current research in Biology

Tag: lifespan

DYING to Know Your Predicted Lifespan? Look No Further!

Have you ever wondered how long you’ll be around for? Well, scientists at the German Cancer Research Center, Saarland Cancer Registry, and the Helmholtz Research Center for Environmental Health have made great strides in predicting human mortality. How so? Through a controlled study in which they analyzed patterns in DNA methylation.

DNA methylation, an epigenetic phenomenon, occurs in the body in order to inhibit the transcription of DNA. Methyl groups attach to specific combinations of DNA building blocks called CpGs. In this experiment, the scientists analyzed the DNA from blood cells taken from 1,900 participants fourteen years prior. As they were all older adults, many of the participants had died within that fourteen years. The scientists analyzed methylation at 500,000 of the CpGs, trying to figure out if there was a correlation to chances of survival. Spoiler alert: at 58 of these CpGs there proved to be a strong correlation between methylation level and mortality.

One interesting discovery was that 22 out of the 58 influential CpGs were identical (in terms of amount of methylation) to the CpGs of smokers that the scientists had analyzed in a previous study. What does this mean? Smoking definitely leaves its mark on your genome. However, the good news is that DNA methylation can be reversed, so if a smoker quits his or her risk of dying could drop significantly.

The second major finding of this study was that only 10 out of the 58 CpGs can actually determine mortality risk. The scientists took the 10 CpGs with the strongest correlation with mortality and created an epigenetic risk profile. This profile can predict “all-cause mortality”. Participants who were overly-methylated at five or more of these spots were seven times more likely to die in the fourteen year span than their properly-methylated counterparts.

This study is a major breakthrough in understanding human mortality, because analyzing DNA methylation is so much more accurate than looking at SNPs. The researchers plan on using their new knowledge to find out how to improve methylation profiles at these CpGs.

Does it surprise you that only 10 spots on the genome can have such a profound effect on duration of life? Do you think there could be an even more accurate predictor of mortality than DNA methylation levels? Let me know in the comments!

Don't Smoke!

Credit: Nina Matthews Photography, URL:

Original Article:

Evolution of Human Lifespans


(Locutus Borg, Wikimedia Commons)

Humans have started living longer and healthier lives. According to research conducted by various international teams, the last two centuries have had a greater percent increase in human lifespan than the past millions of years did.

The research teams compared the average lifespan of the most developed societies to the average lifespan of modern-day hunter-gatherer populations, which most closely resemble the lifespan and lifestyle of early humans. The researchers found that developed countries, such as Sweden, have average lifespans of eighty years now (an increase from the mid-thirties range it was in 200 years ago). On the other hand, hunter-gatherer populations such as the Hadza in Tanzania live only ten to twenty years longer than wild primates.

Such drastic improvements in human longevity are attributed to the advent of several post-industrial era features, including modern medicine and supermarkets. However, males trail behind females in terms of lifespan by at least three to four years– something that has not changed since the beginning of primate history.

The exact reason for the lifespan gender gap is unknown. Some hypotheses propose that males are more at-risk because they carry one X-chromosome and one Y-chromosome, as opposed to the females’ two X-chromosomes, which makes males more susceptible to disease. Another possible explanation centers around harmful male-related behavior, such as fighting. What do you think is the most likely reason for the gender gap?

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