We humans are funny creatures, getting wrought up at the most mundane and trivial differences between us such as politics, race, color, nationality, religion and on and on, when in reality our differences only seem large in our minds; we, and all living things, are remarkably the same, and science says we all arose from a single source about 3.77 to 4.5 billion years ago.
Based on the best available science, all the diversity we see, including humanity, whose ancestors first stepped on the world stage a mere seven million years ago, arose and developed step by step in the chemical bath of the early ocean in the formation of cell components; mitochondria and chloroplasts that joined into archaic bacteria and eventually into us.
The early fossil record of microscopic life is extremely broken and fragile, but Professor Philip Donoghue, Bristol's School of Earth Sciences, wrote in "A timescale for the origin and evolution of all life on Earth," published August 20, 2018, in Phys.org, "Fossils do not represent the only line of evidence to understand the past. A second record of life exists, preserved in the genomes of all living creatures."
By making use of this method the team at Bristol and Mark Puttick from the University of Bath were able to derive a timescale for the history of life on Earth that did not rely on the ever-changing age of the oldest accepted fossil evidence of life.
"Using this approach we were able to show that the Last Universal Common Ancestor of all cellular life forms, 'LUCA', existed very early in Earth's history, almost 4.5 billion years ago — not long after Earth was impacted by the planet Theia, the event which sterilised Earth and led to the formation of the Moon. This is significantly earlier than the currently accepted oldest fossil evidence would suggest. This result is testament to the power of genomic information, as it is impossible, based on the available fossil information, to discriminate between the oldest eubacterial and archaebacterial fossil remains."
The study confirms modern views that the eukaryotes, the lineage to which human life belongs, together with the plants and the fungi, for example, is not a primary lineage of life.
Professor Pisani added: "It is rather humbling to think we belong to a lineage that is billions of years younger than life itself."
The common denominator in life from then to now is a double helix comprised in two chains of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C). The order of these bases is what determines DNA's instructions, or genetic code.
Theoretically, the genetic code is universal. This means that the same codon "means" the same amino acid in all organisms. For example, in both humans and bacteria, a codon made of three thymine DNA-letters will code for an amino acid called Phenylalanine. There are about twenty amino acids, and about 64 codons.
Now, take a great leap forward to about 525 million years ago when the first vertebrates, or animals with a notochord, a primitive backbone, appeared, and by 400 million years ago spiny ray fish began showing up in the fossil record.
And something amazing happens; nearly all vertebrates from then to now, be they fish, lizards, whales, birds, dinosaurs, mammals, turtles or humans, share some basic skeletal features: a skull, a spine. Fins, wings, arms and legs that go from one bone to two bones to several bones to fins fingers or toes ... even bats have fingers.
While the structure is the same, the form differs, each to our own niches and needs.
"Okay," you'll say, "but humans are gifted with an opposable thumb! We can make things the animals can't."
That thumb is indeed a great anatomical development, but it's by no means ours alone. Other animals with opposable thumbs include gorillas, chimpanzees, orangutans, and other variants of apes; certain frogs, koalas, pandas, possums and opossums, and many birds have an opposable digit of some sort. Many dinosaurs had opposable digits as well.
What sets ours apart is our dexterity, made possible by our brain, which is in many ways more highly developed than those of nearly all other forms of life.
Some scientists believe that dolphin brains are nearly as complex as ours, but, living in water and lacking thumbs, dolphins are unable to take advantage of the one thing that sets humans apart from all other animals, a development that can be traced back only about 400,000 years; the ability to control and use fire.
From that developed all the marvelous technology we have today; from primitive campfires to fiery ascents of rockets to the moon.
And in the process of achieving our concept of greatness, we somehow became divided. By religion, by race, by politics, even by something as silly as the DNA controlled color of our skin, eyes and hair.
We all want and need basically the same things; food, love, security, shelter, clothing, a purpose, to explore. To learn and grow. And yet we waste our potential chasing chimeras; dominance, power, money and other illusory attributes that, at base, mean and are nothing.
Perhaps, in time, we'll evolve to embrace our differences as strongly as we now eschew them; we'll learn to fit into our environments rather than keep trying to make our environment adapt to us.
The good news is that our environment, our Earth, is far more resilient than we are. If we don't learn these critical lessons, and soon, our time as part of the environment will ere long come to an ignoble end.