If Grackles Had Teeth!

Each morning through much of May, I had a few reliable visitors check out the suet block and the sunflower cache, stored in a few bird feeders near by. Announcing their presence with a clearly audible screech, not unlike that of the feared velociraptors in the Jurassic Park movie series, was notice for smaller birds to move out. Sporting a well defined beak and watchful, almost glaring eyes, the Common Grackle is nothing short of impressive. I can’t shake out of my imagination the idea of a direct lineage from velociraptors to grackles. This got me wondering: Did birds ever have teeth? If they did, why (thankfully), did they lose them?
Developments in scientific research over the past decades, applied at the University of California in 2014, resulted in interesting discoveries. A 2015 publication in Science, reveals the story of tooth loss. Essentially, all birds have a gene that deactivates the formation of teeth. Amazingly, researchers traced this gene back to the common ancestor of all modern birds which lived 100 million years ago. How this was accomplished is fascinating. Scientists used a genome database that catalogues the genetic history of nearly every all 48 living bird orders. Within that database, one gene, responsbile for dentin, the substance that makes up teeth and another gene that forms enamel to protect those teeth. Once found, scientists located the mutations that deactivated them. The next step was to go through the fossil record to determine when these mutations developed. Fossils of the Ichthyornis, revealed the transition. The back of the jaw had teeth, while the front of the mouth showed the existence of a beak. The loss of enamel was more precisely dated in the research, with its loss 116 million years ago.
Why birds lost their teeth has been open to speculation. The first bird, Archaeopteryx, flew, wore feathers and had teeth, debunking the the theory that birds lost teeth to the load during flight. Another idea put forward was that the birds lost their teeth as an evolutionary change to speed up hatching. Developing teeth within an egg would add length to the incubation period, making the unborn birds more vulnerable to predators. Scientists believe that developing teeth would take up 60 percent of incubation time. Birds could hatch in weeks, compared to dinosaurs which took months to devleop and hatch. A third theory is linked to the impact of the massive asteroid that hit earth 66 million years ago, efectively wiping out dinoasaurs. Out of the necessity of survival, birds developed beaks to adapt to a changing diet that consisted of seeds that could be grasped and cracked more effectively with a beak.
I must admit I am more comfortable watching modern birds. Beaks of different shapes and sizes have a range of purpose. Thankfully, none include the chewing of human flesh at this time. A chicken with genetic mutations, examined in 2006, was found to have teeth, similar to those of a crocodile. Scientists have been able to re-activate the gene to growth teeth. Would you believe that scientists in Japan are devleoping a genetically targeted medication that may allow people to grow new teeth and hope to have it ready for use by 2030. Now that’s something to chew on.