The Expanse of Time – Galaxies, Evolution, Lifetimes

Have you ever seen those amazing composite images that people will post, showing the same picture every day or every year for a long period of time.  We see how children age, how people transform their bodies, and how their day to day experiences, though seemingly small, add up to incredible changes as the years go by.  I personally love time-lapse photography, representing a long period of time in a shorter instance.  For me the beauty is showing those changes that are subtle in human experience and communicating them in a way that shows how significant they are when we have the ability to see them through different eyes.

There is a very important concept that these kinds of videos illustrate, and it’s that seemingly non-existent changes, or changes that are imperceptible on timescales of human experience, are mind-blowing when we can look at the overall difference.  It’s a good life lesson that great accomplishment can be achieved with small changes that add up over time.

From an astronomical perspective, there are painfully slow changes that occur in the universe.  Changes that, over millions and billions of years, show the universe evolving like fireworks.  Take a galaxy collision for instance.  Two galaxies of hundreds of billions of stars, rotating once every few hundred million years, and moving toward each other across a distance of thousands of light years.  To a human being, a lifetime of observation reveals no apparent change, but when a simulation of the immense timescales is produced, and compared to real life observations, we can gain an understanding of how the process unfolds over Billions of years.

Without the technology and simulations to take this massive amount of time and dilute it down to a manageable scale for a human being, we would have no understanding or appreciation for such a marvelous event.

I’m going to use this with one last example, evolution by natural selection.  The response from those who do not understand the concept is to ask the question of ‘how one species can turn into another.’  It’s the same process as before.  Let’s use an example of some ancient creature that ate the leaves from trees.  This animal reaches as high as it can to eat leaves, stay strong, and reproduce.  As hundreds of thousands of these animals are born, reproduce, and die, somewhere along the line a tiny mutation in DNA, a copy error in the reproductive process, it gives one of these animals a slightly longer neck.  The mutation was equally likely to give the animal a shorter neck, or different coloured hair, or any one of a trillion other different mutations, but this one mutation that resulted in a longer neck happened to one member of this species during the thousands of years they have roamed the Earth.

Now this creature with the slightly longer neck, it could reach leaves that were a bit higher on the trees, so it inevitably was able to eat more food.  This made it a healthier creature, and more attractive to the opposite sex.  It reproduced more, and passed on this same mutated gene for a slightly longer neck to some of its offspring, though not all of them.  Those offspring that had the slightly longer neck also could reach higher branches, eat more food, become healthier and more attractive, and were able to in turn produce more offspring that their shortner-necked friends.  Again the mutated genes were passed on.  This happened again and again until eventually the majority of the species had the advantage of the slightly longer neck, and any members of the species who didn’t couldn’t eat as much, produce as much offspring, or pass on their genes as efficiently.

After enough generations, we end up with a creature with a slightly longer neck.  Maybe it took a few hundred years, maybe a few thousand, but once this particular mutation gave the creature an advantage, it worked its way through the entire population for generations until all of them possessed it.

Now at the same time, other mutations have been happening to other groups of our leaf-eating animals, and since there are hundreds of thousands of them, it is likely that some of these groups would be isolated from others.  Some of the traits caused by these mutations may have been detrimental, like weaker vision.  In this case the animal would be more likely to be eaten since it couldn’t identify a predator as quickly, and eventually those animals with the mutation would die out, even if it took a few generations.  Some others may have been advantageous, like brighter coloured hair that would make the animal more attractive to the opposite sex.  Again in this case the advantage would lead to more offspring and would eventually become the norm in the group.

But what if our two successful groups of leaf-eaters never had contact with each other? If they were too far away geographically they would never inter-breed and share the good genes.  And so one group would have slightly longer necks and another would have slightly brighter hair.  There would also be other groups over thousands of years that would develop other beneficial traits that would be preserved, while other groups would have detrimental traits and would eventually die out.

Tree of life unfolds over billions of years.

If we keep repeating this process over large amounts of time, say hundreds of thousands of years, eventually the individual groups of leaf-eating animals that never had contact would be very different from one another.  So different in fact that if they did meet, they could no longer reproduce.  At this point they are actually different species.  Both descended from the same leaf-eating species from long ago, and both are very different than their ancestor.  This is evolution by natural selection, and where we get the ‘tree of life’ concept from.

With such incredible amounts of time, live on Earth has naturally evolved for 3.5 billion years, into us!  This means that if you go back far enough, we share ancestry with not just apes and other animals, but all creatures, plants, everything!  And it’s all a consequence of the laws of the universe.

The incredible amount of time that has passed has allowed so much to happen, and it is difficult to comprehend because as humans we have such a short time to be alive.  But I consider myself lucky, because I have the technology and scientific understanding to see how the universe has unfolded over such incredible timescales.  I have access to a depth of knowledge that I could never have reached without the work of millions of men and women who have lived and died before me.  I have the ability to see beyond the horizon of any species that has come before, and feel connected to the deepest truths of nature.  And I can know that after I am gone, time will continue, until all life on Earth is gone and lost to the vastness of the universe, as one tiny instance, near one tiny star, in one galaxy, in a vast cosmic ocean.

Leave a Reply

Your email address will not be published. Required fields are marked *