Humanity’s oldest ancestor was a tiny Packman-like sack with bad breath

Introduction:

Photograph of the fossilised remains of Saccorhytus coronarius.
Figure 1: Photograph of the fossilised remains of Saccorhytus coronarius. Credit: Jian Han via Nature.

Scientists (Han et al., 2017) have just discovered well-preserved fossilised remains of humanity’s oldest ancestor (Figure 1).  The little dude—your greatest grand pappy—was called Saccorhytus coronarius.

Details:

Where, when and how old?

S. coronarius lived in the seafloor during the early Cambrian period in what is now China (Han et al., 2017). That means S. coronarius lived 540 million years ago. So, how many “greats” should we put in front of grandfather for old S. coronarius?  Well, today the average female generation is about 25.5 years.  However, our ancestors would have lived much shorter lives and we can’t be sure how short.  So, for the sake of estimation, ease, and fun, let’s just assume a 10-year generation.  That would mean S. coronarius was our great x 54-million-grandfather!

What was this thing?

S. coronarius was a Deuterostome. This means that it was an animal that developed its anus before its mouth as an embryo. Just like we do!  (Yeah; you could poop before you could eat—otherwise you would have run the risk of being full of shite!)

S. coronarius was about 1 mm wide and had a very simple body. In fact, it’s body was so simple that it likely only had one opening (Figure 2). Yep, your greatest grandfather made due without differentiating its entrance from its exit!  I can imagine him now, lamenting my easy lifestyle: “You have a mouth!? When I was a kid we used to have to puke our poop!  Don’t know what you’d need two holes for.”  S. coronarius also had no appendages, so it likely moved through the seafloor sand by wiggling (Han et al., 2017).  Thus, our oldest relative was a tiny, Packman-like bottom-feeder with horrible breath.

An artists rendition of Saccorhytus coronarius, a sack with one hole
Figure 2: An artist’s reconstruction of Saccorhytus coronarius, humanity’s oldest ancestor. Credit: Jian Han via Nature.

Conclusion:

If you’re feeling down, you can always take comfort in the fact that you evolved an anus.  Also, you can be happy that you weren’t a dentist during the “good ooooooOOOOoooold days.”

References:

Han, J., Morris, S. C., Ou, Q., Shu, D., & Huang, H. (2017). Meiofaunal deuterostomes from the basal Cambrian of Shaanxi (China). Nature. http://www.nature.com/nature/journal/vaop/ncurrent/full/nature21072.html

Jared Peters

Jared Peters

Jared Peters, PhD, is a geoscientist who specialises in marine sedimentology, marine palaeoglaciology and climate change.
Jared Peters
Did you like this? Tell the world!
Follow Jared Peters:

Jared Peters, PhD, is a geoscientist who specialises in marine sedimentology, marine palaeoglaciology and climate change.