The evolutionary Big Bang: The Cambrian Explosion

Dr Irengbam Mohendra Singh
I have in the past, upstaged the generally accepted theory of the ‘Big Bang’ as the origin of the Universe. I join scientists who remain traumatised by their failure to find the last word in the theory of the ‘Evolutionary Big Bang”, also known as the ‘Cambrian Explosion’.
Remember science is a growing discipline. It’s as yet unable to explain what was there before the Big Bang or, prove the existence of God. That doesn’t mean it never will. It took aeronautical scientists 70 years to figure out how to build the world’s largest passenger jet Airbus A380 (2005) from the 1935 two-engine propeller Dakota aircraft DC-3. Rome wasn’t built in a day, but they were laying bricks every hour.
The Cambrian explosion means a sudden burst of evolution with many different types of animals, many with hard shells living in the sea. The name Cambria was the Roman name for Wales, which was used by Adam Sedgwick, an English geology professor at Cambridge, when he fist studied the sedimentary rocks there.
The theory holds that, beginning some 541 million years ago and within a period of about 10 million years, a huge number of multi-celled organisms appeared on Earth ie five times faster than the normal evolutionary process. Though considered to be due to many factors, it is not quite clear what triggered it. The period lasted 53 million years. The Cambrian period is the first ‘geological time period’ in the Palaeozoic era or the “Time of ancient life”.
This big dent in Darwin’s theory of evolution remains unsolved. Scientists are unable to attach it to any part of the ‘evolutionary tree of animals’ in the way Meiteilon detaches itself from the ‘Tree of languages’.
There are more than 30 theories as many scientists are paid to argue about it. I’m tempted to believe in the combined abiotic (nonliving) and biotic (living) hypothesis because of (1) Leibniz’s philosophy of the “Principle of sufficient reason”; (2) archaeological fossil findings in Burgess shale; and (3) particle physicists’ view that all life forms are made of atoms. Atoms make molecule, and there are a variety of molecules that came with the Big Bang, leading to many forms of life including us.
The 4th century theologian St Augustus wrestled with ‘what was before God created the universe’. He came with a brilliant idea that “Time was a part of God’s creation, and there simply was no ‘before’ that a deity could call home.” I agree with his logic in that there didn’t have to be anything before the Big bang.
We know the hypothesis of the ‘primordial soup’ as the origin of life, as claimed by JBA Haldane 80 years ago. Now it has been challenged by Dr Nick Lane et al, from University College, London. Their theory is that it was Earth’s chemical energy from hydrothermal vents on the ocean floors which kick-started early life.
My hypothesis coddles that certain life forms (biotic) created from chemicals (abiotic) at a different evolutionary stage might have been thrown out by a burst of hydrothermal vents 541-2 million years ago. Such lifeforms might have been created by chemiosmosis acting across a vast array of microscopic organisms at different geochemical gradients, and thus synthesising the universal source of energy, ATP (Adenosine triphosphate). That perhaps led to the appearance of different primitive ancestors as found in the Burgess Shale.
The ‘abiotic’ origin of life is not new. The ancient Greeks thought about the question of what we are made of. Leucippus and Democritus came to nearly as close as to the modern scientific view that we are made up of the smaller building blocks of matter, the amino acids that are made up of atoms, like rocks or donkeys. Atoms and molecules came with the Big Bang.
Amino acids, the building blocks of proteins or ‘life’, have been discovered deep inside ancient rocks, suggesting complex carbon chemistry happening out there in space. As a result, scientists believe that life on Earth might have been formed out in the space and brought to Earth my meteorites and asteroids.
In the eternal philosophical puzzle of ‘where do we come from’, modern science has its own creation theory, based on the view of particle physicists and biochemists, who can prove that we are made up of atoms created in the first few seconds after the Big Bang. In fact, they can tell us what everything in the world is made of, and where it came from. To make some sense out of it, we have to understand the history of the Universe.
Modern science complements the ancient Greek concept that our body is made up of atoms. It wasn’t only in Greece. In Hindu philosophy, in the Bhagavat Gita, Krishna says to Arjuna about the transmigration of the soul (2.13): “Just as a soul acquires a childhood body, a youth body and an old body during this life, the soul similarly acquires another body after death. This should not delude the wise (cf. author’s Quest beyond Religion, p28).The recycling of life and death underlies the Hindu cremation ceremony, with the conviction that from the Universe we came and to the Universe we return after the soul has left the body.
The Bible also agrees with this philosophy that like Adam who was made from inanimate matter, we came from dust and to dust we shall return (Genesis 3:19).
The Burgess Shale was discovered by Charles Walcott, an American palaeontologist and geologist in 1909, and named it for nearby Mount Burgess, in Canada. The shale is dark fine-grained sedimentary rock composed of layers of clay, silt and mud. Walcott wrote: “The Burgess fossils tell nothing less than the story of the Cambrian explosion – ‘evolution’s big bang’, when relatively simple organisms rapidly diversified into the source of animals that live today.”
So far, about 150 species of animals, algae and bacteria have been collected. It’s estimated that up to 98% of the fossils from the locality are entirely soft-bodied. The remainder 2% is represented by animals with parts that were originally ‘mineralised’ like the coveted trilobites, the most typical Cambrian marine deposits around the world. Trilobites are amazingly diverse group of animals (20,000), relatives of scorpion with a segmented body and jointed appendages.
One plausible theory entertains that during the Cambrian period, life was restricted to the world’s oceans. The land was barren, uninhabited, and subject to erosion. These geologic conditions led to mudslides, where sediment periodically rolled into the seas and buried marine organisms. Before this period, living organisms were small, simple and unicellular. It lasted 55.6 million years. Though complex multicellular organisms gradually became more common in the millions of years immediately preceding the Cambrian, none could be fossilised because of lack of mineralisation of the Earth.
It was first stipulated by William Buckland in the 1840s. Charles Darwin in 1845, granted that it could be the main objection to the theory of evolution by natural selection. He wrote: “Lack of fossil evidence for the evolution of Cambrian trilobites must at present remain inexplicable; and may be truly urged as a valid argument against the views here entertained.”
Unlike elsewhere, Burgess Shale gives scientists a clear understanding of the nature of early ‘evolutionary burst of life’ from elements. So far 60,000 unique fossils have been found. The first discovered fossils were trilobites. The most common Burgess Shale fauna is called the Lace Crab, with other dominant arthropod fossils (of animals without vertebrae like crabs, lobsters and insects).
Most of the animal groups (phyla) we see today were found in fossils dating back to the Cambrian period, including rare fossils of soft-bodied organisms like trilobites that were inhabitants on the ocean floor and probably entombed by underwater mudslides near the end of the Cambrian Period.
The Burgess animals are now found also around the world in the Cambrian strata of Greenland and China. Evolutionary scientists argue that the major candidates as precursors of the Cambrian animals are the Edicarian fauna that were discovered in 1947 in the sandstones of Edicaria hills in south Australia. The major forms of these ‘pre-Cambrian’ fauna are soft-skinned, multicellular lifeforms dated 575-550 million years ago. It seems though, they do not have any clear relationship to the fauna of Cambrian explosion.
It’s remarkable that Burgess Shale deposits have been able to explain the evolution, though there are substantial gaps in our knowledge of the earliest animals. Some suggested that Darwin would have invoked his standard argument to resolve this uncomfortable argument, by saying that the fossil record is so imperfect that we do not have the evidence for most of life’s history.
I’m happy for Darwin and myself, as an article (1995) by three scientists, Eric Davidson and Andrew Cameron from California Institute of Technology in Pasadena, and Kevin Peterson of the University of California, Los Angeles, appeared in Nature, to commemorate the 100th anniversary of Walcott’s discovery, that “virtually all animal groups alive today were present in Cambrian seas. And for the Cambrian explosion at least, larval development is the key. They say the trigger for the Cambrian explosion was the arrival on the scene of a class of cells that are held in reserve during larval development, but come into play later to create the adult body form (Science, Vol. 270, p 13190).
(The writer is based in the UK.

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