I actually know a bit of backstory about this photo - it was a series on child labor in the south, and these are photos of oyster shuckers for the Maggioni Canning Co. around 1912.
I'm assuming shucking oysters are rough on the hands, so it could be wounds, but it also looks like crusted-on dirt, so I'm not sure.
Here's another photo where you can see their hands a bit better:
I just wanted to add about the stares. Photos back then required the target to be very still ao they are just probably trying their best to keep still.
Most photos of children failed because they moved. These were very still, hence the tension in their eyes, or just a lucky shot. Anyways, photos from way back always look like death for this reason.
Reminds me of the grim (or beautiful, depending on how you look at it) practice of photographing the deceased, especially children, during the Victorian era. Dressed up and posed, sometimes with living family in the same photo. Part of the reason being the exact fact that they wouldn't move during the shot.