It's About Time ...

TARDISTime! It flies, passes, goes by. It can seem fleeting or endless. Here we look specifically at its biological aspects - how life has developed over time; how circadian rhythms regulate our lives; how organisms grow and develop; and how timing is everything. 

This webguide has been developed in conjunction with an exhibit in the lobby of the Northwest Building at Harvard University. It is timed to coincide with "Time, Life and Matter: Science in Cambridge," an exhibit at the Putnam Gallery of the Collection of Historical Scientific Instruments (

Our intent in this guide is to offer further information and resources for anyone interested in biological time, regardless whether they visit the exhibit or not. It is a work in progress. Suggestions are always welcome!

Once Upon a Time ...

Current evidence indicates that the universe is approximately 13,700 billion years old. Our own solar system began to form around 4,500 billion years ago, and our moon formed soon after, around 4,450 billion years ago, probably as a result of a collision between the earth and another large object. Today, the moon is still moving away from the earth as a result of that collision.

Single-celled life on earth began around 3,500 million years ago (mya; we'll use this abbreviation throughout). This guide, and the exhibit, explore some of the developments along the way, and highlight the research of Harvard scientists on various aspects of biological time, including ancient organisms, growth and development, and circadian rhythms, right down to the genetic level.

If you would like a broader picture of the earth's history, check out the new Timeline in the Earth & Planetary Sciences section of the Harvard Museum of Natural History, part of the Harvard Museums of Science and Culture. Read the press release here.