We all know that first impressions count, but what about predicting your future? You might not think the same way about the humble handshake again after hearing this news. The Economist reported on the 14th of May, 2015 about a study that intrigued the internet: can the strength of your handshake predict the length of your life? It seems so:
“A paper just published in the Lancet, by Darryl Leong of McMaster University in Canada, reports that a simple way to assess how likely someone is to die in the next few years is to test the strength of his grip.” 
It seems almost impossible to predict the future of life and death, but Darryl Leong’s interesting paper challenges that with science. Leong tested different cultural and socioeconomic population groups from 17 countries using a grip test and the results were surprising. Though there was some variance, the strength of the grip correlated to morbidity and mortality rates:
“Every 50-newton drop below this was associated with a 16% rise in the risk of death, and a 17% increase in the risk of dying in particular from heart disease. It was also associated with a 7% greater risk of having (but not necessarily dying from) a heart attack, and a 9% rise in the chance of having a stroke. Among those with cancer or chronic heart disease, the strong-gripped were more likely to survive the follow-up period than the limp.” 
But correlation does not equal causation. Is the reduced grip strength a precursor to morbidity and mortality or is a symptom?
“Because the study was observational rather than experimental, it is impossible to know whether muscular weakness is causing illness or is a symptom of illness that is already there. That matters. If the former is true, then building up strength through exercise might avert early death. If it is the latter, a person’s cards are probably marked irreversibly.” 
In the end, the authors of the study conclude that both are likely to contribute to morbidity and mortality rates. Though the handshake might alert doctors to failing health, other factors such as hip-to-waist ratio, genetics and health are still important in assessing patient wellbeing.