The concepts of the existence of timeless species essences and of a perfect, harmonious universe were also fundamental for classical (pre-Darwinian) biology. Until the beginning of the 19th century the biosphere was believed in the occident to be created by God relatively recently, e.g. 6000 years, and remained static until today.(4) The species essences were thought to ensure that cows can beget only calves but cannot give birth to horses, cats or ants. Although 'Abdu'l-Bahá defends the concept of timeless species essences he does not support a static world view. On the contrary, he considers this world to be subjected to substantial evolution: "Know that nothing which exists remains in a state of repose - that is to say, all things are in motion. Everything is either growing or declining; all things are either coming from nonexistence into being, or going from existence into nonexistence... This state of motion is said to be essential - that is, natural; it cannot be separated from beings because it is their essential requirement..."(5) 'Abdu'l-Bahá proposes that all things in this world are subject either to growth or to decay.
During the 19th century careful analysis of fossil findings made it increasingly clear that the terrestrial biosphere was, firstly, very much older than had been assumed, and, secondly, was not static but that it changed dramatically through the ages. Since the publication of Darwin's Origin of Species, evolution has become a central subject in biology. In this respect modern biology agrees with 'Abdu'l-Bahá's concept of substantial evolution. In classical as well as modern biology, species essences are equated with a static biosphere and are considered to be incompatible with evolution, and consequently modern biology developed species concepts without reference to species essences. Today, concepts of species essences are widely considered to be inappropriate for biology. According to this view, the "modern" species is defined for an existing population of interbreeding organisms, by a common gene pool. For many modern biologists evolution is not the unfolding of a set of time invariant laws of nature or a God-given natural order, but evolution is believed to consist of new self-creations.(6) According to this view biological characteristics, which are not even potentially pre-existing, are assumed to be created de novo on the path of evolution. From the view point of an essentialist this position implies the evolution of species essences. Such concepts of self-creational evolution clearly contradict 'Abdu'l-Bahá's thesis that humanity mirrors the timeless names and attributes of God.
'Abdu'l-Bahá uses two arguments to rebut concepts of self-creational evolution. In support of the existence of timeless species essences, 'Abdu'l-Bahá presents a modernised version of Plato's argument of the perfect harmonious universe; that is, the argument of the time-invariance of the fundamental laws of nature which is one of the central axioms of modern physics. 'Abdu'l-Bahá states: "As the perfection of man is entirely due to the composition of the atoms of the elements, ... since man was produced ten or a hundred thousand years ago from these earthly elements ... exactly the same man existed then as now. This is evident and not worth debating. A thousand million years hence ... exactly the same man will exist."(7) This argument implies that the possibility to form oil lamps, computers, myoglobin molecules or human beings was present in our universe from the very beginning. Their development or evolution is understood as the unfolding of the inherent properties of the laws of nature, or, in terms of Bahá'í terminology, as particular reflections of the eternal names and attributes of God. In contrast, according to the self-creational model of evolution, there would have been certain time points during the evolution of our universe before which oil lamps, computers, myoglobin molecules or human beings would have been impossible in principle, because the necessary characteristics of those tools or beings were not yet created. By the argument of the time-invariance of the fundamental laws of nature 'Abdu'l-Bahá rejects this strange consequence of self-creational evolution.
In a second argument 'Abdu'l-Bahá shows that timeless species essences are compatible with evolution using the example of the analogy between human phylogeny and embryonic ontogeny: "In the same way, the embryo of man in the womb of the mother was at first in a strange form; then this body passes from shape to shape, from state to state, from form to form, until it appears in utmost beauty and perfection. But even when in the womb of the mother and in this strange form, entirely different from his present form and figure, he is the embryo of the superior species, and not of the animal; his species and essence undergo no change."(8) This argument is similar to those put forward by the Meckel-Serrhs law of classical biology, where the embryo was considered to develop through the lower levels of the scala naturae, and to Haeckel's recapitulation law, where the embryo is assumed to repeat the previous evolutionary stages.(9) 'Abdu'l-Bahá, however, merely uses the resemblance of human phylogeny and embryonic ontogeny as an analogy.
Although, the embryo starts single-celled and during its growth evolves through many different stages and develops its form, size and organisation, throughout this process the embryo maintains its human identity. The information stored in the genes remains time-invariant and guides the evolution of the embryo. Without this constant blueprint the development from a simple single cell towards a highly complex organism would be impossible. During its development, the embryo unfolds the inherent properties stored in its timeless genetic information. Similarly, as time-invariant Newton's laws rule the motion of molecules and planets, so does the genetic information in the cells of the embryo guide ontogeny, species essences providing the necessary background for the evolution from the primeval soup towards complex organisms and ecosystems. These species essences represent the names and attributes of God, the "space" of possible forms of life, the "composition and arrangement" produced "through the wisdom of God and His preexistent might."(10)
With the concept of substantial evolution 'Abdu'l-Bahá agrees with evolution biology that life evolves, that the development of life is essentially dynamic. 'Abdu'l-Bahá's concept of the originality of the species, assuming timeless species essences, potential eternal reflections of the names and attributes of God, stands in vivid contrast to philosophies of self-creational evolution,(11) and of the formation of a complex universe from a trivial origin.(12) According to 'Abdu'l-Bahá, our universe is complex from the very beginning, and reflects the eternal, inherently complex names and attributes of God. It is grounded in a complexity which totally surpasses human imagination: "O Children of the Divine and Invisible Essence! Ye shall be hindered from loving Me and souls shall be perturbed as they make mention of Me. For minds cannot grasp Me nor hearts contain Me."(13)