I confess.

I'm jealous of frogs, lizards and salamanders.

Why?

Because of their stem cells and transdifferentiation potential.

Compared to them, us humans are pathetic in terms of our ability to heal ourselves, regenerate body structures, and change our bodies.

I was out taking a hike here in Yolo County today along Putah Creek.  In the last two weeks the place has been literally crawling and hopping with critters including lizards and frogs. Baby frogs and grown up frogs.

I saw an interesting looking spotted frog and took a picture with a zoom lens. I thought I probably had a good picture of a grown up frog--nothing too exciting, but when I came back home and uploaded the pictures to my laptop, I noticed something very cool.

This frog had a tail!  Look closely.

You see this was no grown frog, but was somewhere in between a tadpole and a mature frog. It had not yet lost its tail. But if you look carefully at the tail, it looks like it is starting to wrinkle up and I think it will fall off in the next few days.

I am always amazed at how frogs undergo such a dramatic metamorphosis, some of which is driven by stem cells. By comparison, human development is pretty boring.

The lizards crawling all over the place at Putah Creek and elsewhere are also amazing because if something is chasing them and grabs onto their tail, they can drop it off and regrow a new one! Talk about a remarkable ability to regenerate a tissue!

At best humans can regrow the tip of their finger if it gets cut off. Lame humans!

There was an article in the past week from the Tsonis lab in Nature Communications about the striking regenerative capacity of salamanders. They can regrow many different body parts including stunningly, the lens of their eyes. Researchers showed that this lens regeneration function, which is a stem cell-dependent function, surprisingly does not seem to diminish with age or with repeated loss of the same tissue structure.

If you are a human, the retention of regeneration capacity with age is not much consolation since we start out without much of any ability to regenerate organs anyway.

However, the studies on so-called "lower" organisms that have near complete regenerative capacity nonetheless may someday provide insight into how to unlock the potential ability of humans to regenerate tissues. Even if we never can regrow limbs or even digits, studies on creatures like lizards and salamanders (which when it comes to regeneration are really the "higher" organisms) may very well provide clues for stem cell-based regenerative medicine more generally.

We have a lot to learn still and some of it from creatures that seem far removed from us humans.