Peter Thiel, billionaire tech investor, has revealed a somewhat unsavory interest in the blood of the young. Thiel, like many other Silicon Valley billionaires, is interested in prolonging life expectancy and escaping death. But, unlike Google’s Calico project, or Oracle Founder Larry Ellison’s $430 million foundation to fight aging, Thiel has a particular interest in medical vampirism.

Thiel’s interest, he has said, is primarily personal. In the past he has taken human-growth hormones and investigated calorie-restricting diets. Now he is interested in parabiosis, the practice of using blood transfusions from young people to promote longevity. In an interview with Inc magazine it emerged that a member of his venture capital company has reached out to the Monterey, California, company Ambrosia. Ambrosia recently conducted a trial entitled "Young Donor Plasma Transfusion and Age-Related Biomarkers”, in which blood from the under-25s was injected into the over-35s. Each participant was required to pay $8,000 to participate in the study.

In scientific circles the potential of blood (or at least certain kinds of blood) as a panacea to aging is established. In 2006, Nature published a piece entitled “Stem Cells, Aging, and the Quest for Immortality" on how stem cells can be harnessed in the war against death. Research into parabiosis began in the 1950s but is only now beginning to take hold in the academy. In addition to the Ambrosia trial, more advanced testing is taking place in Korea and China.