Happy Birthday Earth

According to the best chronologies of the 17th century, the earth was created by God on this day between 9 am and 9 pm in the year 4004 BC. This was the date established after a long and thorough study of all the records by the Irish bishop James Ussher. There's something about the Irish air that encourages such forthright declarations, but Ussher had moved over to England by the time he gave his final answer so Ireland cannot be blamed.

We make fun of Ussher now, but some of the best minds of the day, including Isaac Newton's, were working on finding earth's start date. The best minds of our century have determined the earth formed about 4.54 billion years ago, possibly on October 23rd. At that time the universe had already been going on for ten billion years since the big bang. That too may have occurred on October 23. We just can't know for sure.

Life began on earth 4.0 billion years ago. This tidy figure is suspiciously similar to Ussher's 4004 BC. By the way, Ussher was progressive for his time in saying that Jesus was born in 4 BC and not 0 AD as the most people believed. Ussher then packed all previous history into a 4,000 year span.

First of all, let's get some perspective on just how big a billion is. When our kids were in school one of them brought home a charming book called "How Much Is A Million," I just dug it out of the archives. It had several interesting ways to picture big numbers. Here's one: If you counted to a million, it would take 23 days. If you counted to a billion it would take 95 years.

With that in mind, return to life's beginnings 4.0 billion years ago, give or take. Bacteria are our great grandparents. Once the molten earth cooled off and water began to form, the bacteria took off. But they didn't do much for three and a half billion years. Oh, some of the bacteria invented photosynthesis which produced oxygen which was needed for further life's development. Still, even with oxygen, it was billions of years till something more advanced came along.

Half a billion years ago the earth began producing a huge diversity of life forms. Sadly, 99% of all species that have ever existed have gone extinct. But we still have 10 to 14 million species left, of which only 14% have been described. Some scientists claim there are currently a trillion species on earth. It would take 200,000 years to count to a trillion.

Coincidentally, the first recognizable humans appeared 200,000 years ago. Here's a graphic to think about that span of time. The last 24 pages of this "book" of human history (the blue row at the bottom) is recorded history. So enjoy your coffee and apple pie. It took lots of hunting and gathering to figure out how to get them right.