Biomedical Researcher Leonard Hayflick Dies at 98

August 21, 2024

Leonard Hayflick, a renowned biomedical researcher, passed away at 98, on August 1, 2024. He was famous for his discovery related to how cells divide and age, which has dramatically changed our understanding of biology and aging.

What is Hayflick Limit?

The Hayflick limit is a concept that describes the number of times a normal cell in the body can divide before it stops. Typically, a cell can divide about 40 to 60 times. Leonard Hayflick discovered this in 1961, showing that human cells have a limited lifespan. The reason cells eventually stop dividing is that each time a cell divides, a part of its DNA called telomeres gets shorter. Telomeres are like protective caps at the ends of chromosomes, and when they become too short, the cell can no longer divide. However, certain cells like germ cells (which produce eggs and sperm) and stem cells can avoid this limit because they have an enzyme called telomerase that can rebuild the telomeres. Understanding the Hayflick limit has been crucial in studying aging and diseases like cancer, where cells behave differently.

How This Discovery Changed Our Understanding of Aging

Hayflick’s discovery showed that aging is not just about external factors like what we eat or whether we get sick. It also depends on biological processes inside our cells. As cells reach their division limit and stop working, the overall functioning of our bodies declines, which is a key part of aging.

Observations Across Different Species

Research following Hayflick’s work found that the number of times cells can divide before they stop varies across different species. For example, cells from Galapagos turtles can divide about 110 times, which is much more than human cells. On the other hand, cells from lab mice only divide about 15 times. This difference suggests that each species has its own biological clock, which affects how long they live.

About Leonard Hayflick

Leonard Hayflick, born in 1928, studied at the University of California, San Francisco. He made important discoveries about how cells age, showing that cells cannot divide forever, which challenged earlier beliefs. His research helped us better understand how aging works and has been important in the fields of genetics, cancer research, and regenerative medicine. He also pointed out the key role of telomeres—protective parts of our DNA—in determining how long cells can keep dividing.

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