Why Are Most People Right-Handed? A New Evolution Clue
- Professor Puddlewick
- 6 hours ago
- 5 min read
Most people are right-handed. In fact, about 90% of humans prefer using their right hand for tasks like writing, throwing, brushing their teeth or using tools.
That might seem normal because we see it every day. But in the animal world, it is actually quite unusual.
Other primates, such as monkeys and apes, may prefer one hand over the other as individuals. However, they do not show the same strong species-wide pattern that humans do. Humans are different because right-handedness is common across almost every culture.
For many years, scientists have wondered why.
New research led by the University of Oxford suggests the answer may be connected to two major parts of human evolution: walking on two legs and developing larger brains.
What Is Handedness?
Handedness means having a preferred hand.
For example, someone might prefer to:
write with their right hand
kick a ball with their right foot
hold a spoon with their left hand
throw a ball with their right hand
Most people have one hand that feels stronger, faster or easier to control. This is usually called the dominant hand.
Being right-handed or left-handed is not about one hand being “better”. It simply means the brain and body have developed a stronger preference for one side.
Why Is Human Right-Handedness So Interesting?
Humans are primates, just like monkeys and apes. Because of this, scientists often compare humans with other primates to understand how we evolved.
The strange thing is that humans show a much stronger right-hand preference than other primates.
A chimpanzee might prefer one hand for a certain task, but chimpanzees as a group are not overwhelmingly right-handed in the same way humans are. This has made handedness one of the interesting puzzles in human evolution.
Scientists have tested many possible explanations. Maybe handedness developed because of tool use. Maybe it had something to do with food, social groups, body size or the environment.
The new study looked at many of these ideas together.
What Did the New Study Find?
Researchers studied data from 2,025 individuals across 41 species of monkeys and apes. They then compared different possible reasons for handedness.
The study found that humans seemed unusual at first. Our strong right-handedness did not fit the usual pattern seen in other primates.
But when researchers added two important human features into the model, humans started to make more sense.
Those two features were:
Walking upright on two legs
Having a much larger brain
This suggests that right-handedness may not have appeared randomly. It may be linked to the way humans changed over millions of years.
Walking on Two Legs Freed Our Hands
One of the biggest changes in human evolution was learning to walk upright on two legs. This is called bipedalism.
Before this, early human ancestors used their arms and hands more for climbing or moving around. But once they began walking upright, their hands were freed for other jobs.
Free hands could be used for:
carrying food
holding children
making tools
throwing objects
building shelters
creating art
preparing food
As hands became more important for skilled tasks, it may have become useful for the brain to specialise. One hand could become better at careful, controlled movements.
Over time, this may have helped push humans towards stronger hand preference.
Bigger Brains Made the Pattern Stronger
Walking upright may have started the process, but the study suggests that larger brains made human handedness stronger.
As human brains grew and became more complex, they became better at controlling detailed movements. The brain also became more organised, with different areas taking on different jobs.
This is important because hand control is connected to brain control.
The left side of the brain usually controls the right side of the body. This may help explain why the right hand became dominant for so many people.
The researchers suggest that as the human brain expanded, the right-hand preference became stronger and more common.
What About Early Human Ancestors?
The researchers also used their model to estimate handedness in extinct human relatives.
Their findings suggest that early human ancestors, such as Ardipithecus and Australopithecus, probably had only a mild preference for the right hand. This means they may have been a little more right-handed than other primates, but not as strongly right-handed as modern humans.
Later human relatives, including Homo erectus, Neanderthals and Homo sapiens, likely had a much stronger right-hand preference.
This creates an interesting pattern: as human ancestors became more upright and developed larger brains, right-handedness seems to have become stronger.
The Curious Case of the “Hobbit” Human
The study also looked at Homo floresiensis, an extinct human relative sometimes nicknamed the “hobbit” because it was very small.
This species lived in Indonesia and had a much smaller brain than modern humans. It also had a body that may have been suited to both walking upright and climbing.
According to the researchers’ model, Homo floresiensis probably had a weaker right-hand preference than modern humans.
This fits the study’s main idea: strong right-handedness seems to be linked to both full upright walking and larger brains.
Why Does This Matter?
Handedness may seem like a small detail, but it tells us something important about being human.
Our hands are central to how we live. We use them to communicate, create, write, build, play music, cook, care for others and solve problems.
Understanding why most humans are right-handed helps scientists understand how our bodies and brains evolved together.
It also shows that human evolution was not shaped by one single change. Walking upright, using tools, growing bigger brains and developing culture all worked together over a very long time.
Are Left-Handed People Different?
Although most people are right-handed, some people are left-handed — and that is completely normal.
The study does not suggest that being right-handed is better than being left-handed. It simply tries to explain why right-handedness became so common in humans.
In fact, one of the questions scientists are still exploring is why left-handedness has continued throughout human history. If right-handedness is so common, why did left-handedness not disappear?
That question is still being studied.
The Big Takeaway
The mystery of why most people are right-handed may be connected to two major changes in human evolution.
First, our ancestors began walking on two legs. This freed their hands for new tasks.
Then, human brains grew larger and became better at controlling detailed movements.
Together, these changes may have helped create the strong right-hand preference seen in humans today.
So the next time you pick up a pencil, throw a ball or use a pair of scissors, remember: that simple action may be connected to millions of years of human evolution.
Source: Püschel TA, Hurwitz RM, Venditti C (2026) Bipedalism and brain expansion explain human handedness. PLoS Biol 24(4): e3003771. https://doi.org/10.1371/journal.pbio.3003771
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