Our earliest ancestor was a plant, not an animal. This most ancient ancestor was a stromatolite dating back more than 3.5 billion years ago or about a billion years after our earth was first formed. Stromatolites consist of blue-green algae that aggregates, creating layers. Even though most of our early ancestors have gone extinct, stromatolites still exist today. A large population is located in the Hamelin Pool in Shark Bay in western Australia.
Stromatolites were the most abundant fossils found in rocks dating to the Precambrian era, from the origin of Earth about 4.5 billion years ago to 544 million years ago. Stromatolites became prolific starting about 2.5 billion years ago, releasing oxygen into the environment which set the stage for animal life. Both plant and animal kingdoms diversified over the years, but stromatolites remained the same since they were able to adapt to many environments and did not require diversification to survive. They formerly existed all over the world, but today they are endangered.
Over billions of years, both plants and animals evolved into large trees and dinosaurs, but there were many mass extinctions that cut off the branches in our family tree. One of the most widely discussed was the death of the dinosaurs, which occurred about 65 million years ago. The K-T boundary or thin geologic line representing the end of the Cretaceous and beginning of the Tertiary ages included iridium. Iridium is found primarily in meteors. This was strong evidence of when the large mountain of a meteor about six miles wide crashed into the Yucatan Penninsula near the town of Chicxulub in Mexico.
Scientists are fairly confident that this meteor caused significant stress on the dinosaur population, but are not certain if this event could have accounted for the mass extinction by itself. However, if you examine the effects of the meteor’s impact, it might be sufficient. The impact set off volcanic eruptions, massive earthquakes, and tsunamis, all sending dust and debris into the atmosphere, where it blocked sunlight for centuries. This created a nuclear winter with temperatures plummeting. There were wildfires all over earth, causing acid rain. This sounds pretty convincing, but there is one more piece to this puzzle.
About this same time, a large volcanic eruption occurred in the Deccan Traps located in the northwestern part of the Deccan Plateau in India. It may be the largest volcanic province in the world, consisting of more than a 6,600-foot depth of basalt lava flows covering an area of 190,000 square miles. When the event occurred, some estimates show that 580,000 square miles were impacted. This would have been a significant event, which when combined with the meteor could have been too much for the dinosaurs.
Some scientists believe that the Deccan Traps eruption occurred first about 66 million years ago, lasting for thousands of years, and then the Yucatan meteor smashed into the earth about 65 million years ago, causing a double whammy which wiped out the dinosaurs. However, it may be more than a coincidence that the Yucatan impact area is on the opposite side of the world from the Deccan Traps. If you place your finger of your right hand on the area where the meteor landed and a finger of your left hand on the Deccan Traps on a globe of the earth, these locations are eerily opposed to each other.
I don’t believe in coincidences. I would argue that the time lines need to be reexamined. It is more likely that the meteor stuck first, which triggered the great Deccan Flats eruption. Whether this occurred 66 or 65 million years ago is not known, but it must have been closer in time than scientists believe.
Mammals were able to survive these events and over time, an animal called Homo erectus popped up in the east African rift zone about 2 million years ago. These hominids were able to stand upright, so we believe that we descended directly from them. Homo sapiens seem to have entered the scene about 500 thousand years ago, and the subspecies Homo sapiens sapiens, which is very similar to modern man, can be found about 200 thousand years ago.
Our subspecies just barely hung on after the mega-volcanic eruption at Lake Toba in Indonesia about 75,000 years ago. This was the biggest eruption that we know about during the history of earth, which caused a nuclear winter just like the Yucatan meteor and Deccan Flats eruption. Our species came very close to being wiped out. There were only about a thousand of our species that survived this event, which explains why all humans are so genetically similar. After surviving the ice age, our species started repopulating the earth about 10,000 years ago.
So the bottom line is that Homo sapiens sapiens has not been king of the earth for very long. In the great scheme of things, we should examine all our ancestors and realize that we are very insignificant in the great scheme of things, not only in the amount of time that we have occupied the earth, but also in our vulnerability to changes. We have been very fortunate that we are right in the middle of a warm, moderate period, but will we survive the next ice age or cataclysm? Time is really not on our side.