According to scientists...

The Universe came into existence about 13 and half billion years ago in a sudden explosion of matter and energy.  Radiometric dating indicates that out of that matter and energy the Earth was formed around 4 and half billion years ago.

In a process that scientists have yet to be able to successfully replicate, the first life emerged on earth in the form of archaeobacteria, a self-replicating microscopic machine composed of complex protein interactions contained in a bubble of two-layered phospholipid.  This occurred when the earth was already a billion years old, about 3 and half billion years ago.

For the next billion and half years these tiny creatures continued to reproduce, changing their chemistry and physical structures through interactions with each other and the rest of the environment until they reached a level of complexity such that the phospholipid bubbles became containers of numerous other phospholipid bubbles, each filled with their own complex machinery.  These newer more complex cells began to function together and eventually developed into the first multicelled life forms with the first animals appearing another half-billion years later.

Around 550 million years ago there was an "explosion" of diversity among the animals.  Some developed bilateral symmetry (left and right sides) and a bony spine supporting a straight posture. 125 million years later one of these bony fish possessing four shouldered jointed fins crawled out onto the land.  The ridges in these fins developed into the five fingers and toes of reptiles after another 50 million years.

Within another 115 million years the five fingers and toes could be found on mammals, hair-covered creatures that generate their own body heat, and nurse their young.  By 65 million years ago a group of mammals developed opposable thumbs, binocular color vision, and unusually large brains for their size.  Hanging vertically from trees by their arms, these primates developed the rudiments of upright walking.  They also developed more sophisticated social systems than any animals before them.

Fully upright walking emerged as hip bones tilted back to support a vertically positioned torso.  The angles of knees and ankles similarly took on new forms more suited to support the weight of a body descending directly from above, while the front angle of the face also became more vertical.  This in conjunction with smaller chewing muscles created more space in the front of the skull allowing these primates to grow ever larger brains.  After the passing of about 60 million years these brains enabled the creatures to make tools from stone, and possibly to use fire.  

As these homonids continued their evolution their brains continued to grow, particularly in the top and frontal areas, those portions of the brain that enable sophisticated abstraction, planning ahead, self-regulation.  At some unknown point these abilities came to include what we call consciousness and identity.  In any case, another 1.9 million years after tool making began the first anatomically modern humans came to be.  

The modern human brain has all of the capacities mentioned above and more: the capacity for the most sophisticated social relationships in the natural world.  The brain can have as many as 86 billion neurons that are capable of staggering numbers of connections with each other.  Neuroscientists often say: it is the most complex system in the known universe.  

Consider for a moment: This system is YOU

The billions of years, the countless critical details, the tremendous complexity.  I believe it means you are special.  I believe it means you are loved.

What does it mean to you?

The images here are from:

By NASA, ESA, and J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team (STScI). via Wikimedia Commons

By NASA/Apollo 17 crew; taken by either Harrison Schmitt or Ron Evans [Public domain], via Wikimedia Commons

By NASA (en:Image:Halobacteria.jpg(Taken from [1])) [Public domain], via Wikimedia Commons

By Duane Raver/U.S. Fish and Wildlife Service [Public domain], via Wikimedia Commons

By Didier Descouens (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

By David Dennis [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

By Author of reconstruction unknown (klimaundmensch.de) Photographed by User:Lillyundfreya [GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/) or CC BY-SA 2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/2.5-2.0-1.0)], via Wikimedia Commons

By Dr. Johannes Sobotta [Public domain], via Wikimedia Commons

Numerical estimates were taken as available from the relevant Wikipedia pages.

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