In a fertilized egg or a germinating spore, a multicellular organism develops from a combination of cell growth and divisions. A single cell divides into two, then four, then eight, then sixteen, and continues doubling while following a carefully directed program. As the cells grow more numerous, the ball of cells begins to exhibit movement as the cells jostle into position, forming a specific pattern of crests and ridges that eventually settle into the physically distinct shapes of our limbs, our faces, and our hearts. In order for an organism to mature, such events must proceed along one precise program, particularly during the earliest minutes and hours of embryonic development. The amazing thing is that for some organisms, like the nematode, a microscopic worm, the divisions and movements of their cells always proceed in the same fashion all the way until the mature worm is achieved: take any two nematode embryos from the same batch of eggs, and they will develop with uncanny synchrony.1 The importance of this identical developmental process is not that the brood of worms reaches adulthood at the same exact time. Rather, the timing is the same because it is exactly optimal to ensure that each cell has just enough time to grow and mature properly, before the next cell division and before the determination of the cell’s ultimate fate, giving rise to the proper pattern of organization required for the emergence of a functional organ. These patterns are not the product of a divine will, despite their elegance and complexity. Instead, they form as a result of molecular gradients and the instructions encoded in an organism’s genome, which work together to orchestrate the process.
On a larger scale, one of the clearest examples of a natural pattern of growth and development is found during the lifetime of plant—say, of a rose. You have probably noticed that the petals on a rose spiral outward, evenly spaced, to create that characteristic and immediately recognizable shape that is the same across hundreds of cultivated species. In fact, if you peer straight down on a rose stem, you might also notice that the leaf branches emerge from the stem in an upward spiral. These spiraling patterns—also easily discernible on succulents, pine cones, and Romanesco broccoli—are not coincidence, but an intention of nature, in order to ensure that the packing of leaves, petals, stamens, and even seeds is optimal and efficient, putting as many as possible into a limited space while allowing for adequate sunlight and oxygen to reach each leaf and access by pollinators to the inside of a flower.2 Such patterns have been slowly optimized over the course of thousands of years of evolution, and few plants have diverged from this meticulous prescription.