What if humans had evolved as birds?

The idea of humans evolving from birds may not be as wild as it seems. Modern humans stand out in the animal kingdom, but the list of evolutionary adaptations that got us to this point is relatively short: an advanced brain, a cooperative social structure, toolmaking, and language to enhance cultural transmission. Some bird species already have aspects of these traits. What if an evolutionary shift had wiped out early humans? Would another species have risen to the same level of success? And, perhaps most intriguing: could bird-like humans fly? Would they lay eggs?

Among the smartest bird species, the best candidate for evolving into a human-like creature would likely come from the genus Corvus. These include crows, ravens, and rooks, and they possess the traits necessary for developing human-like sentience. They have advanced social reasoning [source: Black], the ability to create tools, and their brain contains a region, the nidopallium caudolaterale, that may grant them abstract thinking similar to the human neocortex [source: Veit]. As intelligent, social, tool-using scavengers, they resemble early humans from 2 million years ago. Let’s use crows as a starting point and call this new species Corvus sapiens, or simply Corvids.

Crows possess opposable talons and beaks, which help them grasp and manipulate objects. However, for serious toolmaking, our corvids would need specialized appendages that do not already serve another function. To achieve this, we would have to rewind the evolutionary clock to Archaeopteryx, an early birdlike dinosaur with three claws on its wings. This cluster of bones could serve as the base for small, manipulative appendages. Supported by wing muscles, these hands could function similarly to human hands and arms. Although this development would reduce their ability to fly, it would compensate by enabling activities such as climbing trees to roost at night.

Would corvids still be able to fly if they evolved into humans? Perhaps. Flight has many benefits, including larger search areas for food, faster travel, and access to places unreachable by predators. However, larger brains may require us to give up flight. Both flight muscles and a big brain require substantial calories, so it is unlikely that both could coexist unless there was a new, consistent source of high-calorie food.

Tools could tilt the balance toward the total loss of flight. If toolmaking and usage are mainly terrestrial activities, then evolutionary pressure would favor corvids that spend more time on the ground. This could also result in the loss of their hollow flight bones, replaced with stronger bones to support tool use. However, their wings would likely remain. Trees and cliffs would be ideal nesting spots, and retaining limited gliding ability would still be useful for accessing and leaving nests.

Here comes the tricky part, as we must address one of the most noticeable differences between primates and birds — eggs. Birds don’t get pregnant. They fertilize eggs, but they never give birth to live offspring. This is unusual. Pregnancy occurs in mammals, certain fish like sharks, and some reptiles, such as boa constrictors, which retain their eggs internally to protect the young. But birds, without exception, lay eggs. Even in Antarctica, where live birth might seem the best option, penguins continue to lay eggs instead of evolving pregnancy. Regardless of the other similarities between corvids and mammal-like humans, they would still lay eggs.

The process of egg-laying would necessitate the development of a complex social structure. A lone mother caring for individual nesting families would not be able to transmit complex culture without a form of group behavior. Humans solved this challenge by forming small, tightly-knit social groups, with the most important early cultural transmissions, like language, being passed from parent to child.

For corvids, the bonds between parents and offspring would be less defined. While bird parents do care for their young, newly-hatched birds often imprint on the first moving thing they encounter—whether that's their mother, another bird, or even a predator. If they were to form tribes, they’d likely imprint on the wrong 'mother' frequently.

This could actually work in the corvids' favor as their society develops. Rather than forming mother-child units, any adult could potentially take care of any young. It would be an exaggerated, socially-institutionalized version of what humans do with daycare and schools. The phrase 'Whoops, I guess I’m your mom now' would probably be a common occurrence.

As humans introduced institutions like marriage, the number of caregivers for children grew. In corvid society, however, large groups of eggs could be cared for simultaneously by various adults, without concern for biological parentage. This could result in a hierarchical society where some individuals focus on child-rearing, while others gather food, or it might lead to a more egalitarian society where roles shift throughout life. In either case, a corvid family would consist of fledglings and any adults present when they hatched.

This would also mean corvids likely wouldn’t migrate as much as early humans did, even if they had the ability. They would still need to live in trees, even after constructing their own shelters. They would remain vulnerable to predators, and their smaller size and tree-dwelling lifestyle would prevent them from developing the same relationship with wolves that humans did for hunting and protection. They also wouldn’t be able to hunt by exhausting their prey as early humans did, since they’d lack the stamina and ability to sweat.

Egg-laying demands a stable base of operations for at least part of the year, so corvids might combine minimal hunting with environmental manipulation to gather food. They would likely begin cultivating nearby plants early on and might even develop agriculture much sooner than humans. Additionally, as they would need to maintain trees for shelter, their relationship with the environment would be less confrontational than ours. It’s not a bad image: small, stationary, black-feathered beings, living in treehouses and tending to their gardens.