(…continued from She Blows Hot and Cold)

We live in extremely rare times. EXTREMELY RARE. So rare in fact, that if an intelligent alien species dropped in and visited Earth at any time within the last 2.4 billion years, chances are overwhelmingly likely that they will find themselves in the midst of some deep gripping glacial age. How likely, you might ask? Let’s do the math.

**Total time span:** **2.4 billion years**

**Average Glacial age span:** **150,000 million years per ice age**

**Average Interglacial (warm) span:** **12,000 years per warm age**

Keep in mind that not all ice ages last 150,000 years. The first one lasted three million years, so the numbers are fairly skewed. On top of that, there were five major glacial periods, each lasting beyond the 150,000 year time frame. The numbers I listed above are grossly rounded to make it easier on my arithmetic because I am not too picky with numbers that large. I simply want to find the probability that the aliens will hit an interstitial or warming point on Earth. Without doing any serious calculations, I can already tell at a quick glance that most likely, they will land upon ice, ice, and more ice, with a chance of snow, hail, and more snow.

But you know what, I am a mathematically-challenged Taobabe after all. When I see too many zeroes leading or following numbers, my eyes get glazed over and I lose all sense of proportions.

To make this easier on me, I am going to limit the scope of this statistics problem to the life cycle of Homo sapiens, not the life cycle of Earth, which…as we all know, is a very long time. In fact, Mother Earth is as old as…well—dirt, and we don’t want to go there. We want to find out, within the time that humans have walked the Earth, what are the chances that an alien civilization will find us at our glowing best, within a warm, temperate time zone.

Since Homo sapiens arose out of the woodwork circa 200,000 years ago, we will use that number instead. Now, within the last 200,000 years, we have only had two interglacials, for a whopping grand total of 22,000 years of warm weather. The remainder of that 200,000 years, we were ensconced in varying degrees of cold, cold, and more cold.

So if some aliens decided they wanted to talk to a real live human, they would have to come some time during the last 200,000 years, and to maximize the return for their expended efforts, they would want to land during one of our more temperate time zones because there would be more of us humans around to talk to.

So what are the chances that they would hit a warm interglacial?

(…to be continued)