On Being Old

There are limits for us mortals. Our records tell us that the average male human in 2012 is expected to live for 79 years and the average female will live for 84. That seems to be a good stretch of time, and one that has been boosted significantly by advances in science.

Mark Graham and a cross-section slice of a tree (on its edge) that is as tall as he is.

The author beside a sample taken from a very old western red cedar (Thuja plicata). Image: Mark Graham © Canadian Museum of Nature

But humans do not even come close to being the longest-lived organisms. If you were to go through the collection at our research and collections facility, you would see, for example, a complete cross-section taken from a Western red cedar (Thuja plicata). By counting the rings, one for each year of life, we can see that this sample is from a plant that lived for more than a thousand years—a champion of longevity and an awesome sight to see in cross-section. Some of these beauties still live in well-protected sanctuaries on the west coast of North America, where some individual trees are more than than 2000 years old.

There are some champions in the animal world also. Perusing the fish collection leads us to the sturgeons—some of these freshwater migrants live well over a hundred years. Tipping the life chart more towards infinity are the 2000- to 4000-year lifespans reached by colonies of some corals!

Recently, we have been conducting research in our laboratories on seashell specimens as part of a study on how marine invertebrate communities have evolved following climate warming along the Atlantic coast during the past 10 000 years. In this research, the shells are collected from huge, ancient piles left over from populations that lived along the coast of the estuary and Gulf of St. Lawrence, near Baie-Comeau, Quebec. (Read our blog posting about these amazing deposits).

If you cut a section through a clam shell the right way, you can count the layers to determine age, similarly to how it is done for trees. The difference is that the rings are so tightly packed that a microscope is needed to count them. That kind of work is done in the laboratories of Pierre Blier, Ph.D., and André Martel, Ph.D., by Daniel Munro, a doctoral candidate at the Institut des Sciences de la mer, Université du Québec à Rimouski.

A slice of shell showing growth rings and with a 200 µm scale.

Cross-section through a shell of an Arctic quahog (Arctica islandica) showing the annual growth rings. By comparison, the width of a human hair is around 100 µm. Image: Daniel Munro © Daniel Munro

Their research is aimed at determining how the physiology of some marine clams contributes to attaining such an old age. Research on the Arctic quahog (Arctica islandica) that live around Greenland has shown that these cold-water clams are amongst the oldest-lived individual animals on the planet (different from the longer-lived colonies of coral), some up to 400 years of age.

These bottom-dwellers have limited mobility after their larval stage, when they settle and start growing in the ooze of the ocean floor. As cold-blooded aquatic creatures, their life is strongly directed by temperature, the abundance of food, water chemistry and for some, a special physiology. The patterns of their growth and other features of their shape and size can tell scientists a great deal about the natural environment that existed during their life. Conditions that supply more food and warmer temperatures contribute to faster growth.

These studies help us understand how the environment affected these creatures and others that have a similar lifestyle or that lived among them. The results are also important in predicting the effects of future environmental conditions on existing populations of aquatic life.

Understanding the health of our planet is the most important research associated with these creatures, but there are teams of scientists who are trying to find the secret of long life in clams to see if that might work for others.

These are the discoveries of specimen-based research, something that is common at natural-history museums. One of the unique practices of specimen-based research is the keeping of records—vouchers—of the work for others to see and study further. These vouchers make up a significant part of our collections at the Canadian Museum of Nature.

As part of our ten million specimens we have examples of the first (type specimens), the last (extinct species), the biggest (dinosaurs and whales), the smallest (microbes, such as diatoms and algae), and in some cases, the oldest (the Arctic quahog).

This entry was posted in Animals, Collections, Research and tagged , , . Bookmark the permalink.

One Response to On Being Old

  1. Vic Draper says:

    I believe I may have the oldest White Willow tree in Quebec
    Its circumference is 17.18 feet
    Its estimated age is 195 years
    I am looking for support funding to maintains its health

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