There’s a dinosaur on my window ledge and I don’t know how I feel about it. I can see it sitting there, beady eyes watching me, talons gleaming. Not the plot line for the fifth Jurassic Park movie, just a magpie hanging out. Maybe the talons aren’t full of malicious intent and maybe it’s not really doing anything more than noticing my existence but I definitely wasn’t lying when I said there’s a dinosaur out there. Okay, maybe that’s stretching the truth a little bit. It is true to say that all living birds are modern descendants of a line of dinosaurs that, if capable of logging in to Ancestry.com, would include Velociraptor and Tyrannosaurus Rex.
That magpie isn’t likely to invite these relatives round for dinner, not unless you want your guests to have their faces torn off. So how do we get from a serrated-tooth Suchomimus to a swallow or Deinonychus to ducks: evolution by natural selection. It’s one of the most important ideas in science and the foundation of all biology. When first put forward by Alfred Russell Wallace and Charles Darwin in the 1800s, evolution was the most controversial change in our understanding of our own place in the world and it’s no different today. Despite this, evolution by natural selection is a beautifully simple and elegant process: be alive, get laid, have babies.
What we need to first understand is that nature doesn’t care whether you live or die. 99.9% of everything that has lived is now extinct. Being alive isn’t easy: our environment changes frequently and for the ancestors of that magpie to live to see another day, they needed an edge, to be different. Differences between organisms and species are called variations. In the case of some dinosaurs, there were a bunch of variations that led to becoming bird-like: the presence of feather-like structures (protofeathers), hollow bones to make them lighter and generally being smaller than their ancestors. Looking at this fossil of Archaeopteryx, it’s easy to see how similar birds and dinosaurs can be, with its claws and teeth and tail like a dinosaur but feathers like a bird.
Around 65 million years ago, a 10km wide meteor smashed into Central America, plunging the world into a months-long darkness. With many of the plant life dying, there wasn’t a lot of food around for massive dinosaurs: the herbivores died and with them the large carnivores. Great-grand magpie was lucky to be small enough to get by on eating whatever it could find (dead dinosaurs, worms, insects and the like) and have feathers to help keep warm in those chilly post-apocalyptic nights.
These variations kept great grand-magpie alive long enough to see the competition for potential sex partners die, having been torn apart by predators or starved to death. Even if the competition is still alive, an organism can still have some sort of variation that makes it a better prospect for procreation: maybe it builds the best rock pile, like penguins, or it beats up all the competition, like giraffes. (NOTE: this process is vastly more complex in humans and beating up/killing the competition is NEVER a good option). Build the best rock pile, beat the competition or be handsome enough and great-grand magpie gets to level up to stage two of evolutionary success: getting laid. Congratulations, buddy, you’re now a parent.
Given that our magpie is still hanging around out there, looking for shiny things to fly away with, it’s safe to assume that the babies from great grand-magpie had the winning genes of its ancestors. Look back through a family photograph album and you’ll notice that the children take features from both of their parents (just as my daughter pug takes after me). The offspring from sexual reproduction (there are other, arguably less fun ways of reproducing but that’s a story for another time) are a 50/50 mix of both parents. Winning variations can be passed on to the next generation because they are found in the genes of the surviving or
ganism (genes being the instructions for making living things). Take two winners, give them some privacy and out comes a little baby with a genetic mixture of both parents – level three of evolutionary success. The mix of variations that made the parents such great survivors could be found in the next generation and hopefully survive whatever nature has to throw at it.
And so the story goes on for decades, centuries and millennia; nature picking off those less well adapted to their environment and leaving the most adapted alive. They get laid, have babies and repeat often enough that a new species, genetically distinct from its ancestors, is found. This wonderful process has given rise to some amazing creatures, like dinosaurs, and some not-so-amazing creatures, like the blobfish.
Evolution by natural selection is a brutal, uncompromising struggle for survival where the less adaptable die, hungry and alone, and the successful survive long enough to see themselves in their offspring. Evolution is the most elegant, beautiful and simple way of explaining the awe-inspiring diversity of the living world around us. The next time you see a magpie in your garden just be glad that it is a magpie and not its long-lost evolutionary cousins…
I’d much rather a magpie take a dive at me than a T. rex, thanks. Image source.