What is Hitchhiker's Thumb?

Mary McMahon
Mary McMahon

Someone who has a thumb which bends backward when extended is said to have a hitchhiker's thumb. This is a genetic trait, and it does not interfere with the thumb's normal functions. Hitchhiker's thumb is also not linked with any other genetic conditions; it is simply an interesting phenotype, akin to people who can curl their tongues. To see if you have a hitchhiker's thumb, make a fist and extend your thumb. If you notice a significant bend, you have inherited this trait.

Hitchhiker's thumb is a recessive genetic trait.
Hitchhiker's thumb is a recessive genetic trait.

Hitchhiker's thumb is a recessive trait, which means that people must inherit the gene from both parents for it to manifest. People can also carry the gene without exhibiting the trait, by inheriting the gene from one parent only. Recessive traits are particularly interesting because they can appear to flit in and out of a family with no apparent reason, thanks to the fact that they can lurk in generations of genes before manifesting.

Some people with a hitchhiker's thumb are capable of bending the joint in the thumb to extremes which may look uncomfortable to people who lack this genetic trait. You may also hear hitchhiker's thumb referred to as “hyperextension of the thumb” in a reference to this. There is no particular advantage or disadvantage of having a hitchhiker's thumb, and it certainly does not predispose people to hitchhiking.

Having a hitchhiker's thumb is not the same thing as being double-jointed. People who are double-jointed display a trait known as hypermobility, which allows them to move their joints much further than is normal. In this case, all of the fingers of the hand can be bent and twisted in interesting ways, in addition to the thumb.

The study of recessive genetic traits can be very interesting, because it can reveal intriguing information about family and regional histories. Some teachers like to use the hitchhiker's thumb in classroom exercises which demonstrate the basic principles of genetic inheritance, showing students what a hitchhiker's thumb looks like and then encouraging them to collect data from classmates. In some families, such traits may become topics of discussion and commentary, with children being told that they have “inherited Aunt So-and-so's thumb” to give them a deeper connection with the rest of the family.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments

ambitiousIV

Has it ever been noted if Japanese, Korean, and Native American women have the trait of "hitchhiker's thumb"? What other ethnic groups among women have this trait?

anon997618

I have this..... on all fingers. All will bend back to 90 degrees or more.

anon990234

Here's a fun thing to do with it:

You can make people freak out if you hold your thumb straight and push on it from the top. Then all of a sudden, let your thumb bend back. If you do it well, it looks like you just broke your thumb. It works with many people.

anon968544

There are advantages and disadvantages, Picking a guitar is a lot more challenging, in my opinion. My thumb starts to get sore after a while because when I hold my pick, my thumb naturally bends all the way back. I can't hold the pick normally.

anon357360

It's been my observation that hitchhiker's thumbs is not only genetic but is frequent among Latina, Indian and Vietnamese women. Note Jessica Alba, Jennifer Lopez, Freda Pinto and Dr. Sapna Parikh. And men find this trait attractive in women!

I noted an article in a science and medical magazine that some women are pursuing the surgery to achieve this feature to please and attract men.

anon357347

I have hitchhiker's thumb. There are advantages and disadvantages. Advantages: Unbeatable at thumb wrestling, can give great back massages. Disadvantages: Makes it harder to snap.

anon354265

Both my thumbs bend back and I can also bend the MCP joint on my left hand forward but not on my right. I can also often fit my entire hand through small spaces that friends with thinner hands can't!

anon279529

I remember doing an article in high school about what people will look like in the future, and found out humans are getting taller and more people are becoming double jointed with longer fingers. When I visited doctor for a broken and fractured finger, he saw my double jointed fingers and referred to them as deformities.

My mom quickly defended me telling him those are advances in human evolution and are blessings from our Lord. I have always been stronger than my peers in hand strength and feel truly blessed with my double jointed fingers. I have a history of jammed and fractured and broken fingers from playing basketball and football, but I am proud to be unique and unlike the majority of people. I feel blessed and feel I have an advantage over most people.

So to all double jointed people, I tell them to stay proud, stay strong, work out and strengthen your muscles around those joints you were blessed with. No, you are not deformed. You are the advanced version of human body. --Tim

anon253795

I am 23 and only just came across this. I'm the only person I know with this trait. I can also touch my wrist with my thumb and even bend it past my wrist.

anon117248

my thumb bends all the way back and all the way forward. Can anyone else's?

anon102245

This is so weird. I have hitchhikers thumb and my sister can bend her thumb 25 percent more than me so I think she's double jointed.

anon100656

Is hitchhikers thumb associated with any specific culture or nationality?

anon89429

It's weird. I studied this in biology at school, and realized I have both. A hitchhiker's on the right, and a regular on the left.

anon76538

A 1953 study found that the incidence of the trait in the US was 24.7 percent in white people and 35.6 percent in black people.

anon70522

my thumb is really bent and the other is not, so what do i do?

anon26624

What is the national percentage of those people with hitchhiker's thumb?

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