I just noticed that if I put the heel of my hand in the arch of my foot, my fingers exactly meet the length of my toes. It seems like there should be a developmental biology explanation. Or is it just coincidence?
Coincidence. The homologous bones inside the hand and foot are very different in their size and and proportions.
You might also notice that your foot rests almost perfectly within your forearm, the heel in the crook of the elbow, and the tow to your wrist.
Still, coincidence.
Coincidence that X equals Y. The reason it works (assuming it really does*) for lots of people is that we tend to have grown in propotion with ourselves.
(I just tried it and it works, but I note there is at least an inch of play in the range of positions that I could still reasonably and quite earnestly describe as ‘heel of hand in arch of foot’)
I can’t do this, without actually taking my feet off.
Thanks guys. I know where to come for answers.
Look into Fibonacci Number and nature - there is a ratio that is found throughout nature (including the human body). I’m guessing you’ve found another Fibonacci ratio.
1:1? That is technically a Fibonacci ratio, but not particularly impressive that it shows up in different places (wait, my left arm is as long as my right, my left foot is as long as my right…it is everywhere!)
No, a Fibonacci number (the Golden Proportion) is 1 : 1.618 (0.618 : 1). I’m guessing your hands are 1 to your foot’s 1.618.
A Fibonacci Number is a number from the Fibonacci Sequence (1,1,2,3,5,8,13…). The Fibonacci ratios are the ratios of consecutive numbers in the sequence (hence my joke, 1:1 is one of those ratios, albeit a pretty trivial one), the limit of the ratios as you go up the Sequence is the Golden Proportion.
But the OP was asking why the length of his hand was the same as from the arch to his foot. That’s just a ratio of 1:1, I don’t see how any part of his body having a Golden Ratio to any other part of his body would force his hand to be the same size as his arch-to-toe distance.
Why on earth should there be . . . or would there be?
DO NOT DO THAT. Long story, foaf thing.
The OP is basically asking, “why is my whole hand as long as an arbitrary part of my foot?” Cat Whisperer is suggesting that the ratio the OP found may indicate that the ratio of whole hand to whole foot is a Fibonacci number.
^^^ Yeah, that’s what I’m trying to say. Thanks, Tom.
This isn’t so in my case. My hand is 17 cm long, and my foot 30 cm, for a ratio of about 1.76. Is it so in your case?
The Fibonacci series tends to show up in spirals and other recurrent forms in nature. There is no particular reason to expect it to show up in the ratio between the human hand and foot.
It’s actually not hard and doesn’t require any contortion. Sit in a chair with no arm-rests and cross your leg over the other knee (the male way, where the ankle is on the knee.) Then it’s not hard to bend over and put your forearm up against your foot.
After a certain age, it’s a lot harder than you think.
I’m the Cat Whisperer Whisperer.
Let’s see - my hand is 17.5 cm, my foot is 25.5 cm. Unless I’ve got the math wrong (and that is always a possibility), my ratio is 0.686. Is that close enough for rock ‘n’ roll? 
Given that your hand/foot ratio is 1.457, I wouldn’t consider it at all close to Fibonacci. (I see the smilie, but I’m answering this straight.)
Why would you expect the ratio between a hand and a foot to show a Fibonacci relationship? As I mentioned, the Fibonacci series turns up in natural spirals, branching patterns, and other repetitive series. You wouldn’t expect it to show up as a ratio between two arbitrary body parts.