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Our Last Universal Common Ancestor – LUCA

In keeping with my thoughts on how we as humans came into existence, I thought I’d chat to you about Luca today.  Who or what is Luca?

One of the most important outcomes of modern biology has been the demonstration of the unity of life. All living beings are in fact descendants of a unique ancestor commonly referred to as Luca (the Last universal common ancestor).

This venerable ancestor was a single-cell, bacterium-like organism. But it has a grand name, or at least an acronym. It is known as Luca, the Last Universal Common Ancestor, and is estimated to have lived some four billion years ago, when Earth was a mere 560 million years old.

Common descent is a term within evolutionary biology which refers to the common ancestry of a particular group of organisms. In contrast, common descent can also be traced back to a universal common ancestor of all living organisms using molecular genetic methods.

Luca is the most recent common ancestor of all current life on Earth. Luca is not thought to be the first living organism on Earth, but only one of many early organisms, whereas the others became extinct.

DNA also shows that our species and chimpanzees diverged from a common ancestor species that lived between 8 and 6 million years ago. The last common ancestor of monkeys and apes lived about 25 million years ago.

According to scientificamerican.com, in 1871 Charles Darwin surmised that humans were evolutionarily closer to the African apes than to any other species alive. The recent sequencing of the gorilla, chimpanzee and bonobo genomes confirms that supposition and provides a clearer view of how we are connected: chimps and bonobos in particular take pride of place as our nearest living relatives, sharing approximately 99 percent of our DNA, with gorillas trailing at 98 percent.

Yet that tiny portion of unshared DNA makes a world of difference: it gives us, for instance, our bipedal stance and the ability to plan missions to Mars. Scientists do not yet know how most of the DNA that is uniquely ours affects gene function. But they can conduct whole-genome analyses—with intriguing results. For example, comparing the 33 percent of our genome that codes for proteins with our relatives’ genomes reveals that although the sum total of our genetic differences is small, the individual differences pervade the genome, affecting each of our chromosomes in numerous ways.

I found an interesting video that explains the facts of evolution, our universal common descent in some detail.  It’s roughly five minutes long, so you may want to check it out now or save it to watch later https://www.youtube.com/watch?time_continue=4&v=G0UGpcea8Zg

I suppose that whether or not we are all descendants of one particular single cell organism, whilst very interesting to find out about, is not the most important thing about us being here on the earth. I like the idea that we all share DNA, and again the varying degrees of shared DNA is not important.

What is important is that we, us humans who are known to be the most intelligent species on earth, who have the ability to tell the difference between right and wrong, should be taking the lead in every possible way.  We need to completely embrace the responsibility of looking after the planet and taking care of every living thing on it.  I have been watching a really interesting program on Netflix called One Strange Rock.  A lot of the program is presented by astronauts who have spent days, weeks, months floating around above the Earth.  Their recounting of this amazing place that we call home, is so fascinating to listen to.  They have certainly brought a new perspective to my way of thinking.  And getting to understand that everything is completely interlinked in the most delicate, intricate, but at the same time, violent, all-encompassing way, is just mind-boggling.

So when next you think about your spiritual link to you fellow human beings, to your fellow animal species and to the minerals, crystals etc of the earth, dig a little deeper into those thoughts.  Get yourself to consider how much this planet on which we reside, takes care of us in providing the very thing that we require to sustain life and that is oxygen & water.  And from the provision of oxygen and water, we are able to grow our own food, feed ourselves, experience all forms of life and live out the life that we have chosen to in order to facilitate our spiritual growth.  What an amazing privilege for us all!

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