Tuesday, December 30, 2014

Turning New Year’s On Its Head

The New Year is nearly upon us. This time of year we think of birth, potential, new chances to accomplish goals. The fresh start is symbolized by the New Year’s baby entering as the old man of the past year exits stage right.

Say hello to the dancing baby, perhaps the world’s original viral
video and internet meme. If you remember when the baby first
showed up, you have seen at least 18 New Years and probably
watched Ally McBeal.
Well, I’m going a different direction. I’m interested today in discovering which living things have seen the most New Years babies. It should be easy, just survey all the species of living things on Earth, find the oldest member of each species, and declare a winner.

Unfortunately, it’s not so easy. Do you volunteer to track every naked mole rat to see which one lives the longest? How will we account for the hundreds of thousands, or even millions, of species we haven’t discovered as of yet? Maybe we will just have to use examples for those individuals and species we happen to have data for – that, and maybe some speculation.

A researcher in 1999 proposed a hypothesis that species body mass directly relates to longevity, ie. the bigger the animal, the longer it lives. There are myriad examples that don’t seem to follow his rule, and his hypothesis has met with substantial resistance, but the paper has been cited more than 1500 times so somebody’s buying it. More recent evidence from his group suggests that metabolic rate may be as telling as overall body size. It’s a live fast, die young hypothesis.

One of these images is of Misao Okawa, the oldest living human
as of late 2014. The other image is of Miley Cyrus and some of
her backup dancers. I don’t see Misao, so she must still be
working on her moves (Miley is the one in the middle).
As for humans, Misao Okawa of Okinawa will soon see her 117th New Year’s Day (as of late 2014). She is the oldest female as well as the oldest person, and attributes her longevity to consumption of sushi and a goal of becoming a back up dancer for Miley Cyrus. OK, I lied about one of those………sushi, who’d believe that.

Humans are amateurs when it comes to longevity. Jonathan, a Seychelles giant tortoise (Disochelys hololissa) is said to have seen 182 New Years. This is an estimate; a picture of Jonathan in 1882 shows him to be adult sized, and this takes about 50 years. So they guess he was born about 1832.

Bowhead whales (Balaena mysticetus) are second in size only to Blue whales, and individuals of this species are known to live for 210 years or more, making it the oldest living mammal species. Believe it or not, we can tell this by examining their ears after they die. They build a specific number of layers of ear wax each year, so we can just count the rings, exactly like with a tree – only yuckier.

A new study shows that bowhead whales have altered gene expression that may account for their longevity, especially in terms of fat metabolism and insulin signaling. The same study also shows that bowheads have parallel changes in gene expression that are seen in other species that live longer than one would expect – like the naked mole rat and Brandt’s bat.

The quahog clam isn’t really that big, so it defies the hypothesis
about size and longevity. The bottom image is a micrograph of
a quahog shell. You can count the layers to determine how
many growing seasons it has lived through, not necessarily
how many years. A new study examined the layers to estimate
ocean conditions over the last 400 years.
The ocean quahog clam (Arctica islandica) can live for over 400 years. A recent study indicates that this animal produces much lower levels of damaging molecules in their mitochondria (the energy generators of the cell). If we figure out how they do that we will be able keep our cells healthy for long times.

The oldest living individual organism THAT WE KNOW OF is a bristlecone pine tree in the White mountains of California. It's known to have seen at least 5064 Rose Bowl Parades. People can visit its grove to wish it a happy birthday, but you’ll have to guess which tree is the oldest – only one man knows and he isn’t telling.

In truth, the idea of what is old is not so easy to discern. As humans, we have a prejudiced notion of what “old” means. We are born, we live, we die. The person who remains vertical for the most days wins. But many organisms just don’t play by our rules. As a result, they can “live” for hundreds of thousands of years.

This isn’t the oldest Bristlecone Pine – or maybe it is. The Forest
Service won’t tell anyone which of the pines in this California
locale is actually the oldest. The unnamed tree is 5064 years
old, and shares its forest with another pine named Methuselah,
who clocks in at 4847 years old.
Organisms in harsh environments can just stop growing and go into suspended animation. Humans can only do that in science fiction movies like Interstellar. In the Antarctic, some lichens (a symbiosis of fungus and algae or photosynthetic bacteria) grow only 0.01-1 millimeter each year, and that’s in the good years. They can be in suspended animation for hundreds of years. Does that count as one life or two?

Samples of bacteria were “life suspended” until brought out in a Siberian ice core. Once thawed they began to divide. Are those bacteria several minutes old or 500,000 years old? They wouldn’t be growing and dividing except for the ice coring process. Maybe global warming will bring billions of old species back to life.

Let’s look at another way to circumvent the traditional idea of long life. Quaking Aspen trees (Populus tremuloides) live as colonies of clones. In the Pando clone of Utah, great stands of these trees cover more than 100 acres and constitute the heaviest single organism on Earth – over 6000 tons.

They all stem from one progenitor tree and they are all connected by one root system; roots sent out in a direction will turn upward and give rise to new trunks. Do we count the newest trunk to sprout and the first trunk that may have fallen over 80,000 to 1 million years ago as the same organism and the same life?

When injured, starved or bored, the immortal jellyfish will revert
from adult form to juvenile form and just grow up again. Can you
imagine an infinite number of adolescent periods? Imagine
the parents!
Maybe the weirdest example to demonstrate how hard to determine what constitutes a single life looks like is the immortal jellyfish (Turritopsis dohrnii). Take the name seriously. This small cnidarian lives in the waters of the Mediterranean Sea and off of Japan.

In typical jellyfish species, juvenile jellyfish live as polyps, then become bell-shaped medusae as adults – then die. However, the immortal jellyfish can revert from medusa to polyp and then grow up again. It can theoretically do this indefinitely, making the jellyfish ostensibly able to live forever. In practice, most die from disease or predation, but the possibility of infinite life is there.

One moral of our story – don’t worry about how many New Years Days you may or may not get to see – your number isn’t going to mean anything to anyone else. While studying old things may extend our lives in the future, be sure that you make of the most of the New Year you are being given now.

Contributed by Mark E. Lasbury, MS, MSEd, PhD

Munro D, Pichaud N, Paquin F, Kemeid V, & Blier PU (2013). Low hydrogen peroxide production in mitochondria of the long-lived Arctica islandica: underlying mechanisms for slow aging. Aging cell, 12 (4), 584-92 PMID: 23566066

Seim I, Ma S, Zhou X, Gerashchenko MV, Lee SG, Suydam R, George JC, Bickham JW, & Gladyshev VN (2014). The transcriptome of the bowhead whale Balaena mysticetus reveals adaptations of the longest-lived mammal. Aging, 6 (10), 879-99 PMID: 25411232

Holland, H., Schöne, B., Marali, S., & Jochum, K. (2014). History of bioavailable lead and iron in the Greater North Sea and Iceland during the last millennium – A bivalve sclerochronological reconstruction Marine Pollution Bulletin, 87 (1-2), 104-116 DOI: 10.1016/j.marpolbul.2014.08.005

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