I got to thinking about humanized organisms while I was reading about hydra. Hydra make good models to study the biology of aging because they seem to be immortal: they don’t seem to age at all. If we knew how they accomplished it, it might help us understand how to slow aging. How do we know that they don’t age?
Prof. Daniel Martinez observed groups of hydra for years. He carefully fed them and kept them in separate tubes. Each one was observed making buds – little baby hydra – but the old hydra was put into a fresh tube alone every time. The researchers waited for any of them to get old and die… and none did. Well, maybe they didn’t wait long enough? We can only compare them to other creatures in the same weight class.
Longevity tracks body size and time to first offspring. So orcas (weight 1 million grams, first offspring at 25 years) live far longer than voles (weight 10 grams, first offspring within a few weeks of birth). Hydra weigh in at a fraction of a gram and have their first offspring a few days after being born. But they are still alive and reproducing for years, thousands of times longer than the trend would predict.
What allows hydra to accomplish this? How do they regenerate? What’s special about their stem cells that they don’t deplete? Can we study hydra in a way that’s relevant to human longevity?Continue reading