An Asian American born in Connecticut in 2009 could expect to live89.1 years. An African American, on the other hand, couldexpect to live 77.8 years. Its seldom surprising tosee large discrepancieswhen comparing life expectancies indeveloped and developing nations, considering the vast differences in availablehealth care. But how do we explain such a wide variance between two populations or ethnic groups living in the same region?

The complicated relationship between population, ethnicity and raceand how it impacts our health involves a complex equation offactors,includingmedicine,economics, psychology, anthropology, sociology andgeography. But it also seems clear that there are so-called race-related genetic factors in play .

Cultures and health behaviors

At this point in the history of medicine, there are a handful of behaviors withwell-established health impacts onour health. Among this is tobacco smoking,which has been linked unequivocallyto lung cancer and chronic obstructive pulmonary disease (COPD). Its also associated withcardiovascular and cerebrovascular conditions (leading to high blood pressure, atherosclerosis, heart disease, and strokes), and a host of non-pulmonary cancers. Yet different ethnic groups react differently to prolonged exposure.

Consider that therate of smoking among Native Americans is higher than for any other group in North America, at 26.1 percent, according toAmerican Lung Association. At the other end of the smoking spectrum areAsian Americans, at 9.6 percent, andHispanics at12.1 percent. In the middle areAfrican Americans, 18.3 percent, andCaucasians,19.4 percent.

Source: American Lung Association

Based on smoking rates alone, youd expect Asians and Latinos to have lower lung cancer rates, and they do. However, youd also expect Native Americans to have higher lung cancer rates. Yet their lung cancer rates are only slightly worse thanthose of Latinos. Strikingly, the ethnic group with the highest lung cancer rate is African Americans, according to the Center for Disease Control (CDC).

A similar phenomenon is seen inalcohol use. According to the National Institute of Alcohol Abuse and Alcoholism (NIAAA), the most common drinkers are white males, 74.27 percent, while Asian-American women were the least common, at 36.11 percent. In terms of daily heavy drinking, the highest rates were recorded among Hispanic males, at 40.48 percent, while Asian American men had the lowest rate, at 18.84 percent. Alcohol abuse relates to liver disease, nutritional disorders, and various cancers, but as with smoking the disease rates among ethnic groups do not correlate precisely with consumption.

Black men (25.81 percent)and women (19.02 percent), for example, reported lower rates of daily heavy drinking, when compared to white men and women. Yet, African Americans have a higher risk of developing alcohol-related liver disease, according to the National Institutes of Health.

Health genetics

With majorkillers like heart disease and stroke,there are a multitude of genetic factors, making forcomplex relationships between genetics and disease.For example, despite having a relatively high risk of developing cardiovascular disease, Latinos have alower risk of actually dying from the disease. Thus, studies are constantly underway to examine genetic risk factors and markers. African Americans have a notoriously high rate of high blood pressure compared with other ethnic groups, and for decades there has been a debate regarding whether genetic factors or environmental factors are more important.

What about discrimination?

A potentially troubling possibility has emerged from a University of Florida study that was published in December 2016in thejournal PLOS ONE. By interviewing 157 African American subjects in creative ways, researchers were able to show a relationship between the feeling of discrimination and high blood pressure. The study pointed toeight genetic variants of five genespreviously known to be associated with cardiovascular disease. The cause ofhigh blood pressure iscomplex, given that its related both to physical phenomena such as factors controlling how tightly blood vessels squeeze, as well as psychological factors, since blood pressure rises in nearly everyone when they become anxious or stressed.

Putting all of these factors into a coherent picture of how diseases are generated appears to be a daunting task. Year by year, month by month, the science community is inundated with new data, especiallyfrom genomic studies. Various new instruments are in use too, and yet, when the goal is to assess anything related toethnicity or race, the task grows progressively more difficult.

David Warmflash is an astrobiologist, physician and science writer. Follow @CosmicEvolution to read what he is saying on Twitter.

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Race, genetics and health: Our ancestry both limits and exacerbates ... - Genetic Literacy Project