Why? Simply because the Universe demands it. Now I know this is too simple so let’s elaborate a bit more. What I am going to write is in no way a scientific observation. It is only one possible conclusion after observing the evolution of life on Earth and drawing a hypothesis as we venture into space.
Life started on Earth on a microscopic level. For billions of years, the only organisms found on the planet were single cells. Tiny little elementary living things. Then about 600-800 million years ago (yes, plus or minus 200 million years!), life jumped to a whole new level and multicellular organisms appeared. The cat was now out of the bag and life exploded on the evolutionary scale during the Cambrian Period (541-485 million years ago).
Single cells, with a lifespan of days to months, came together and created organisms that lived longer and got bigger. What started primitive and became more complicated. If Life wanted to step up its game and evolve, it had to scale up and develop new tools. And it did. Over hundreds of millions of years, Life experimented and pushed the boundaries seeking longevity and reach. Before you tell me not every organism opted for this strategy, let me jump ahead and agree with you. Life plays on all levels at once: the micro to the macro, the big to the giant. There are, though, themes that we can observe and agree on. With the dinosaurs, things got big – too big. Unsustainably big when on land, but possible when in the water. It is believed that the average life expectancy for high-metabolism dinosaurs was anywhere between 10 to 60 years, while some low-metabolism giants like the Apatosaurus could live in the hundreds. From the perspective of evolution, a slow and long strategy might not have been the best solution. What is needed is a sweet spot: not too big and not too small. Something that lives long enough to mutate and adapt. Something that doesn’t die too quickly but also doesn’t live forever. Unless you have the capacity to force mutation yourself, evolution wants a fairly quick turnover.
With the rise of mammals, sizes, and longevity in general stabilized. Fast forward to the Paleolithic Era when humans were expected to live for around 30 years. With the rise of technology and the complexity of our species, our lifespan slowly increased, although it didn’t move much. Up to the 1950s, the world’s average was 46 to 48 years of age. As we started to control diseases, famines and fought less, age expectancy shot up to the average of 73 years today. If you are looking for a great read, I suggest Homo Deus by Yuval Noah Harari.
Now if we were limited to the Earth, our environment would counterforce this adaptation and mutation. The capacity to live longer and healthier would actually become too much of a burden on the resources. Scarcity in space and food would perhaps force a reduction in size and longevity. But if the increase in numbers and technologies does the opposite effect and creates the incentives and tools to look beyond the Earth, then we are embarking on a whole new evolutionary journey.
The scale of the Universe is simply too big for our current biology and technologies. But all that will change.
Back in the 1840s, if one wanted to travel from New York to San Francisco, there were only 3 very costly choices: overland via the Oregon Trail which took more than 6 months; sail south around the Cape Horn, a 200-day perilous journey; or via the shortest route, sailing down to Panama and portage across, then sailing back up. In 1852, Lieutenant Ulysses S. Grant opted for the Panama portage. While he made the trip in 6 weeks, from his regiment of 700 people, only 450 made it to San Francisco due to cholera outbreaks. Today, you can fly across the world for little (comparatively) money, almost zero risks, and in a very short time. Your cost in time and energy is almost nothing, while 170 years ago, it was excessively high and often mortal.
Right now, it takes 3 days to go to the Moon. That is without counting all the preparations and training needed. If you want to go to Mars, better be ready to invest 7 months of travel and many more to simply get ready. A round trip will most likely commit you for 2 years. And if you want to travel further, to let’s say, the closest terrestrial exoplanet candidate, Proxima Centauri b, it will take you 4 years to get there – if you can move at the speed of light. Once there, and after missing the Earth you decide to come back and embark on another 4 years at light speed, you would arrive on Earth with most of your friends and family much older or dead, because of Time Dilation. Time-wise, it simply doesn’t make sense. Just like swimming across an ocean is ludicrous. And that is only the challenges of travel and time. On the biology side, the obstacles are monumental; for now.
But just like what was impossible 200 years ago and now is taken for granted, we will adapt and mutate so that we can expand the reaches of Life into space. Life will scale up to the Universe in the same way that it scaled up to the Earth. Within our lifetime, we will see small gradual changes and yes, breakthrough technologies, but the big evolutionary mutations and adaptations will take thousands of years when we get to live for 500 years and more. Will we be bigger? For that, I really don’t know. Perhaps a bit, perhaps not. There again evolution will have to find a sweet spot. Being too big increases all the energy costs and that might not be the most sustainable solution when traveling long distances.
We are a product of our environment. Since the beginning of our species, we have been playing in a sandbox. But now, as we look up to the sky and plan our next space move, our sandbox is about to become the size of the Sahara. If you are an ant that lives for several months, getting across that box is no small feat but totally feasible. But in the Sahara, you wouldn’t live to see the end of the first day. Our initial space travel will be hard, deadly, and complicated, but as we find ways to mutate and adapt, both with technology and through evolutionary biology, space exploration will become as common as traveling from New York to San Francisco on a jet.
PS. Our perception of time will adjust. The ant is not experiencing time faster because it lives only for 4 years. When we get to live 500 years, that half-century will be perceived in a similar fashion we perceive 100 years today.
PSS. Yes, life expectancy will increase, there is no doubt about it. That said, immortality will never be achieved. Death is a constant of Nature and a necessity for Life.
Recommended read: The Next 500 Years by Christopher E. Mason
