Beginnings of Universe and Life

In order to fully contemplate life on this planet, it is important to understand the environment in which life has formed and developed. 

The Universe – feeling small

The cosmos we are able to observe and measure with our eyes and instruments began nearly 14 billion years ago with a “Big Bang”.  The cosmos appears to be contained at its edges and there are estimated to be 3 to 7 × 1022 stars.  In other terms, this is 30 to 70 billion trillion stars….a totally immense number that is difficult to imagine.  There are also more than 80 billion galaxies in the cosmos.  When we view the Milky Way at night, we are looking into the center of the flattened spiral that is our own galaxy.  Our own galaxy contains 200-400 billion stars, yet the closest one to our own sun is Proxima Centauri, which is 4.3 light years distant. Our imagination cannot begin to envision the size of a Universe that contains 30 to 70 billion trillion stars.  Yet, despite such an immense number of stars and the fact that we are in a galaxy of such stars, our nearest neighboring star is 4.3 light years distant.  The size is beyond typical comprehension.

Each of the above facts builds on the previous ones to reveal that our own little solar system is barely a grain of sand in an ocean.  Even so, our solar system is much larger than we can comfortably experience in our lifetimes; the distance to the sun is 93,000,000 miles, or the equivalent of 38,000 trips from New York to Los Angeles.

Earth and Early Life

In 2001 the Wilkinson Microwave Anisotropy Probe (WMAP) was launched by NASA to make fundamental cosmological measurements of our universe as a whole.  Analyses of those data have enabled a refinement of the age of the universe to 13.73 ± 0.12 billion years.

Numerous sources provide estimated timelines of the formation of the earth and evolution of life on our planet. The Earth was formed at nearly the same time as our solar system - more than 4.5 billion years ago.  Therefore, our Earth is roughly 1/3 as old as the universe itself.  The first life, consisting of simple cells, occurred 4 billion years ago.  Life has existed on planet Earth for 80% of its existence.  The materials and conditions to support life existed relatively soon after formation of the Earth when the environment was still very hostile. The primordial mix of matter from which our planet formed and the conditions provided by planet Earth as located in this solar system enabled life to begin relatively soon after the Earth formed.  Given the immense size of the Universe, and the relative ease with which life formed and has flourished on Earth, it seems very plausible, even likely that Life exists elsewhere in the universe.

Evolutionary timeline

For the first 3 billion years of life on Earth, life forms consisted of single cell organisms.  The earliest forms of life existed in extremely hot environments such as around hot underwater vents heated by molten rock.  Although current life forms still exist in such hostile environments, these conditions would be unlivable for most current forms of life.  These early single cell organisms derived their energy from the heat of their environment.  About 3 billion years ago, cells developed photosynthesis to derive energy from the sun and the oxygenated environment.   About 1 billion years ago, multi-cellular forms of life began to emerge.  However, these multi-cellular organisms did not have significant body forms.  Organisms at this time were simple and composed of individual cells occasionally organized into colonies such as sponges.

About 543 million years ago (mya) there was a huge advance in life forms.  This was the beginning of the Cambrian Period which has been referred to as the “Cambrian explosion” and also as “Evolution’s Big Bang”.  During the Cambrian Period there was rapid appearance of most major groups of complex animals.  Most current living organisms can trace their roots to animals that developed during this period. Life in the Cambrian Period was exclusively in a water environment. 

During the Cambrian period (543-490 mya) all parameters of the common basic body plan developed.  These included a bilateralism of body design with a head, tail, appendages, gastrointestinal track, notochord, and beginning of neural concentration in the head.  Animals with jaws, mouths, teeth, claws and tentacles developed. Sexual reproduction, which laid the foundation for genetic variability and rapid evolutionary growth, appeared during this era.

A key attribute of the Cambrian life forms is the existence of hard, external body parts.  Animal forms prior to this time had soft sides or tissues.  Some of the animal forms that appeared in the Cambrian explosion likely had soft predecessors from the Pre-Cambrian period, but the remains of soft animals did not survive time as well as the hard skeletons of the Cambrian period.