Good genes in the family tree

This summer, I move to Califor?nia to work at Fresno Pacific Univer?sity. On my weekends, I am looking forward to visiting some of the oldest organisms in the world, which are several trees found on the mountains and coastal plains of the western U.S.

The coast redwood Sequoia sempervirens is an evergreen tree, some of which reach 1,800 years. This species includes the tallest trees on Earth, reaching to 379 feet. While endangered, it is also readily cultivated outside its native range. Thanks to cultivation, the campus of Fresno Pacific University, deep in California?s Central Valley and about two hours away from natural stands, contains several large examples of these trees.

But there is a tree that puts the coastal redwood to shame in the longevity category. The bristlecone pine Pinus longaeva lives in the White Mountains of Califor?nia, and one living individual might be more than 5,000 years old.

It is amazing to think of an organism sitting on the mountains for millennia, watching as stars are born and die, the climate changes for 1,000 years and then reverses, massive floods occur in the valleys below, and thousands of falling stars pound the Earth.

Why should organisms live so long? Can?t they get their business out of the way after a few years?

It turns out that a lot of animals could ask that about us. Humans live a long time compared to other animals of our size. Why? And you may wonder, who asks such questions in the first place?

Biologists are interested in these types of questions. Biologists classify organisms into two very basic categories: those that have a lot of offspring at a young age (r-selected), and those that have a few offspring spread over many years (k-selected).

Sunflowers are an example of r-selected plants, which produce all their seeds within one growing season, and the old evergreens of California are examples of k-selected plants, spreading their seeds over the centuries.

If plants live in inhospitable environments, such as the White Mountains with unpredictable weather patterns, they might evolve longevity so that at least a few of their seeds can get a foothold in a lucky year.

Humans, of course, each have far fewer offspring than either sunflowers or pine trees, even if one were to include the Duggar family. Humans are definitely k-selected organisms.

But there is an even more unusual aspect of the human life cycle. We quit having babies at about half-way through our lives, but then, if we are lucky, hang around for another 50 years.

Most other organisms die during or immediately after their reproductive phase. Many senior citizens have termed this phase of their life cycle the ?golden years.?

Biologists would point out the important role that old persons play in training the younger generation. Humans have a huge set of learned skills, such as speaking, hunting, tool-making, peace-making and war-making, that take decades for an individual to develop and refine.

Humans were likely selected to live far beyond our reproductive years because of the advantage of extended training of the next generation. Besides our parents and grandparents, our training now includes advice passed down through the millennia in written form. We can see what worked and did not work in political systems, natural resource extraction, sexual systems, and now scientific findings.

Thousands of years ago, King Lemuel was instructed in the Book of Proverbs to listen to his mother. The rest of the Bible is also teeming with commands and advice to respect parents and elders.

Creation Care Club of Tabor College created a T-shirt a few years ago with a drawing of the Earth?s sphere and the phrase ?Respect your mother.? This is good advice, both literally, metaphorically and biologically.

Andrew Sensenig will begin work as assistant professor of biology at Fresno Pacific University in fall of 2015. He can be reached at andrewtsensenig@gmail.com.

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