Thank You, Cousin

Homo sapiens is the sole human-like critter to have survived millions of years of primate evolution. One by one, the other hominid species died out—either because they were less fit for their niche or because we may have out-competed them and drove them extinct. The last of our hominid cousins (Neanderthals) disappeared tens of thousands of years ago—leaving us to dominate the planet.

DNA analysis has gotten increasingly accurate in recent years, to the extent that we now know that at some point we interbred with those most recent cousins of ours. Some 4% of our DNA comes from Neanderthals (who left Africa far sooner than our human ancestors did, headed for west Asia and Europe). When we followed them to Eurasia, we coexisted with them for a few thousand years and even had sex with them. Similarly, the recently-discovered Denisovians also departed Africa ahead of us and migrated into East Asia. Since 6% of our DNA comes from them, some of our ancestors must also have mixed it up with the Denisovians.

It’s interesting to contemplate why this interbreeding may have occurred, especially when these two closely-related species looked so different from us humans. (No one yet knows what a Denisovian may have looked like, since we know about their existence only by the discovery of a finger of one of them. The DNA analysis was able to show that they were a separate species.) Our hunter-gatherer ancestors traveled in small bands and tended to look upon other bands of humans as alien and not quite human. So ancient humans must have regarded Neanderthals and Denisovians as even further from allowing any possible relationship, and yet the evidence suggests they did get it on.

Maybe on those long, cold nights during glacial periods, it may have been any port in an ice storm. I could see the temptation to snuggle up with a hairy, warm body as just too great to resist. A warm and fuzzy dog or cat can be a blessing when the temperature drops. It’s also possible that individuals of one species were captured by another species, and found some attraction coming over them, in time. I’m thinking of white people being captured by American Indians (or vice versa) 300 years ago, and then later mating. (I have intentionally avoided considering the possibility of forced sexual relations, although that may well have happened. I’d like to stay upbeat and focus on consensual coupling here.)

So what may have been the result of a little cross-species hanky-panky on the part of our deep ancestors? For one, it may have fostered a little peaceful interaction between these different hominid species—think of Pocahontas’s supposed intervention to save the life of John Smith and later marrying Virginian Thomas Rolfe. Colonial period liaisons such as this certainly could have saved a little blood from being spilled—which may have also been true for humans and Neanderthals.

Recent scientific research has discovered another benefit from our cross fertilization with Neanderthals and Denisovians: it gave a boost to our human immune system. Those rare interbreeding incidents introduced new variants of immune system genes into us—in fact, the study shows that some of our stronger immune system genes came from our hearty cousins. (One interesting ancillary fact that arose from this work is that people from today’s Africa have fewer immune system genes than Europeans and Asians, because their ancestors stayed in Africa and did not get the opportunity to mate with those other extinct hominids.)

So the next time you see a drawing of a Neanderthal, don’t think about how they seem inferior and uglier than we do… feel a little gratitude for the diseases you haven’t had, thanks to those ancient cross-species romances. Thanks, cuz!

Coltsfoot Bloom

Coltsfoot is spring's first bloomer around here. A true joy! Other popular names: tash plant, ass's foot, bull's foot, butterbur, coughwort, farfara, foal's foot, foalswort, horse foot, and winter heliotrope. I think I like coltsfoot.

Blink of an Eye... Part 2

So, our universe is just a baby; it’s just getting started. How do we wrap our heads around the span of time left? How do we grasp the vast length of time the cosmos still has—the billions and trillions of years that will yet roll by, when we humans survive a mere few dozens of years? Here’s one way to try: Let’s equate the length of time over which Goldsmith predicts that the last star in the universe burns out (a good way to view it as the lifetime of the universe), to the 80 year span of a human lifetime. His estimate for the last star to wink out is 100 trillion years from when the universe was created. That’s when the grand old cosmos will be on its last legs; just as an 80-year-old human can be equally considered to be on her last legs.

So how do the some of the salient events in the life of the universe compare to the life span of an octogenarian human? One of the first major events in the history of the universe (for us Earthlings) was the formation of our sun and its solar system. The genesis of our own star and its planets occurred when the universe was about eight billion years old—the equivalent of a 2 ½ day old octogenarian! This is a scale we can comprehend: our solar system came into existence when our 80 year-old person was not even three days old! Talk about just getting started!

So where are we today in this young universe, at some 13.7 billion years of age? It is equivalent to a four-day-old infant who will live to see 80. Still a mere start! We’ve 79 years and 361 days to go, before it’s all over! What else can we look forward to, in the future? Well, the last of the universe’s stars will form when the cosmos is 100 billion years old. That equates to our octogenarian reaching the age of one month! 

The message that this brings to me is: We humans (even our Earth) are nothing to the longevity of this cosmos we so temporarily inhabit. We are far less than the blink of an eye to the grander universe. In this context, how can we think that we amount to much of anything, let alone be the reason it all came about?

Let’s explore this age equivalency a bit more, just to drive home the point how minuscule we are. The human species has been around for about 200,000 years. In the life of an 80-year-old person, that amounts to about five seconds of existence. Five seconds in 80 years! That’s all that Homo sapiens¸ amounts to! That’s nothing! Another example: The good ol’ US of A has been a nation for some 236 years now—a decent length of time, eh? Well, that’s only some six seconds in the life of our venerable octogenarian.

To me, these examples emphasize our irrelevance to the grand scheme of things. Was the universe created for us humans? Are we the center of it all? Get over it, folks! We amount to almost nothing, when it comes to the Creation. Does this mean that we are relegated to a meaningless existence? Is this a bummer of a message? Should we go into a funk and despair over our miniscule lot in the grand scheme of things? Despite the fact that our proud human story tells us we are the culmination of the universe’s unfolding, it ain’t necessarily so.

Some people who buy into the exaltation of the human condition may want to deny the truth of this blink-of-an-eye situation and hold onto the old myth. However, I believe there is a deeper message, once we get past the notion of our self-inflated image. I think we all can agree that this universe is a wonderful, sacred creation. That sacredness is manifested everywhere around us. Some people consider this to be God as evidenced in the material world. That may be so. Whatever one’s interpretation, the material universe’s magnificence is beyond our comprehension.

The bottom line, the magnificent truth, is that we are a part of this grand thing. Not only are we humans graced to be alive, but also we have been given the consciousness to understand the precious nature of this gift. So what if it’s not all created just for us… I’ll celebrate the great fortune of just being an aware part of it!

Blink of an Eye—Part 1

 The March 2012 issue of Scientific American magazine has a fascinating article by Donald Goldsmith, an astronomer who once served as consultant on Carl Sagan’s 1980s Cosmos television series on PBS. In his article titled “The Far, Far Future of Stars,” Goldsmith points out that, while the glorious period of star and galaxy formation in our universe is largely behind us, the universe has a very, very long time yet to go, before it becomes a doddering, failing entity. In fact, this grand cosmos we inhabit is just getting started. It is yet in its infancy, at 13.7 billion years of age, according to the latest scientific understanding. Many exciting events are yet to come, and one of those, Goldsmith says, is that the universe will become increasingly conducive to life, as it ages further.

That, to me, is a remarkable fact, given the rapidly changing understanding in the scientific community, that the presence of life in places other than Earth is far more likely than we previously thought. Humanity has historically tended to believe that, in this entire universe, the solitary location of life has been our tiny planet. We are most special, according to this line of thinking, and are divinely delegated to be the single island of life and consciousness in this immense cosmos.

That self-centered perception is wrong, I believe. We still have a very limited understanding of the universe, and we are finding new facts every day. The more humanity has opened up to another-centered perspective, the more we have come to comprehend the reality of this incredible cosmos. Forms of life recently discovered in unlikely places on our planet are indicating that life can thrive in far more inhospitable locations than we once believed. There is an increasing understanding that life may well exist “out there” somewhere and we will soon prove it to be true.

Returning to Goldsmith’s message: There is a lot more history to come, in our fantastic universe. It is now a little shy of 14 billion years of age. In its very beginning, hydrogen and helium were the only elements existing in the nascent cosmos. The first stars were formed from these gaseous elements (99% hydrogen and 1% helium). When they quickly burned out (over just a few million years), they collapsed and the high internal pressures formed a few heavier elements—such as carbon, nitrogen, and oxygen. As subsequent stars formed over the next few billion years, more and more heavier elements were forged.

Eventually, there were enough heavy elements (maybe then 1% of the total  matter in the universe) that when a star formed, there was enough solid material present to form planets. When our cosmos was about eight billion years old, our sun materialized out of the existing local stardust, with enough solid material left over to form eight planets (nine, if you are old fashioned and wish to include Pluto). It required another five or so billion years to bring about complex life on this planet.

So what is the prognosis for our five billion year-old solar system? In another five billion years our sun will use up most of its nuclear fuel and will swell up to a red giant star. That process will toast the inner four planets, after which the sun will collapse into a white dwarf and slowly recede into oblivion. Any life aboard planet Earth will have long before been incinerated.

Meanwhile, in the rest of the universe, events will slowly, slowly wind down. The emphasis here is slowly… really slowly. After the Earth will be long gone, the universe will be just coming into its stride. The stars that form after our sun dies will have even more heavy elements and will last much longer than our sun. These cooler stars will harbor many more planets than our current cosmos holds and they will live for far longer—trillions of years, rather than billions. Life will have many more opportunities to arise and flower, in this far distant future. That forthcoming cosmos may be teeming with life.

More on the aging universe next time…

Recent conjunction of Moon, Jupiter, and Venus (Venus at bottom)