The Embryo’s Eloquent Form

Stephen L. Talbott
This essay is part of a work in progress and is subject to continual revision. Original publication: May 22, 2008. Date of last revision: March 18, 2013. Copyright 2008 The Nature Institute. All rights reserved.

Given the importance to us of questions about our own origins and destiny, and given all the conflicting views about our place in the cosmos, it’s odd how rarely anyone thinks to look at our human origins and try to answer the questions directly. Where do we see the nascent human being coming from and going to? Can we not allow the new arrival to speak for itself?

Listening to how the developing embryo “speaks” for itself has, in fact, been the long-time interest of the anatomist and embryologist, Jaap van der Wal.

Giving and Receiving

In the fall of 2007 I sat in a workshop as van der Wal projected onto a screen a series of images showing how a human embryo grows its arms, starting from the point where each arm appears to be nothing but a primitive precursor of the hand growing directly out of the “shoulder.” As the arms grow, the hands reach forward, around, and slightly downward in a grasping gesture rather like an embrace. Having completed this movement, the arms (as they continue to grow) briefly move apart somewhat, with the now much more hand-like hands turning in a palms-up direction, as if giving or receiving something.

Embracing, giving, receiving: it’s a fascinating sequence to watch, in some ways no different from the countless human gestures we see every day. But, of course, there is a great difference. The embryo is not using its arms in the way we do; it could hardly use its muscles and joints, given that it is busy growing them. What I was watching was in fact a gesture of growth - a gesture by which the arm and hand were being formed, as opposed to the later activity of an already formed limb that has become more or less fixed in its anatomical structure. But there is nevertheless an intimate relation between this first growth gesture and the later use of the arms, since the movement of growth is shaping the means for the later activity.

In purely mechanical terms, there are many ways the arm and hand might emerge from the early embryo. Therefore it is noteworthy that the actual gesture of growth already expresses something about the c