If you knwo the fundamental force driving the system then some "asssumptions" (which often makes an "ass" out of "u" and "me") can be made in the model. We can 'assume' the force is constant over the period of evaluation and and we can assume some intial t=o starting point for an exact formulation of convenience (instead of a general formulation of true knowledge).
However, we do not know even know the fundamental force driving the system. All we have are heuristic observations that exclude the forces driving reproduction.
We have certain components of the formula but not other modulating or forcing functions that prevent the current formulas from expiring, converging or diverging wildly.
In the grand schem of things we know practically nothing. Those who are in the business will also admit to that.
Yet we have no evidence to exclude Divine origination. none.
So what kind of scientist excludes, a priori, a possible complete solution without any evidence to support that exclusion?
There are certain basic assumptions that science uses because without them science is not possible. One of these is that there are testable, natural explanations for all natural events. Another is that the laws of science don't change over time and from place to place in the universe.
Surely you can see that without either of these assumptions, science isn't possible. Without the first, there's no point in even engaging in science. Why should you seek a natural explanation for a phenomenon when there may not even be one. By your standard, which involves rejecting the second assumption, we cannot do ANY science, let alone any science involving life. We don't know for certain, for example, that gravity operated in the same way several million years ago as it does today. We don't know for sure that the laws of chemistry are applicable to the early earth.
However, in the interest of actually doing some science, we provisionally assume that the laws of science remain constant throughout time and space. We can check the consequences of that assumption and determine whether this assumption leads to absurdities in some cases. For example, we are pretty confident, but not entirely sure, that the force of gravity works on Pluto as it does on earth, mainly because we assume it does and then calculate where Pluto will be based on that assumption. If Pluto is found to be in a position slightly different from what we have predicted, we look for explanations for that based on the assumption that gravity indeed works the same everywhere. If there's a difference that's too big to explain by the gravitational attraction of other bodies, we would then reject the assumption that gravity works the same everywhere. In that case, we would probably NOT reject the assumption that the laws of science are constant everywhere, but rather look for a more fundamental idea that explains the differing gravities on earth and Pluto.
A similar idea is at work with respect to life. We do indeed understand the basic forces at work with life. They are mostly just manifestations of the electromagnetic force, which is well understood. We do indeed assume that the electromagnetic force, in its manifestation known as the laws of chemistry, works the same way in living creatures as it does in test tubes full of chemicals. We do understand the basic principles involved, what we may not understand in all cases is the detailed application of these principles. In mathematical terms, this would be analogous to knowing all the differential equations governing life, but not knowing any initial conditions sufficiently to yield an accurate result. Much of this arises from the complexity of life. This is analogous mathematically to a chaotic system of differential equations. A infinitismal change in initial conditions can produce a finite change in the solution of the system. Therefore, unless these initial conditions are known to a great deal of accuracy, prediction is not possible. Nonetheless, it cannot be said that we have no understanding of the basic forces of life.
If you are postulating that there must be some heretofore unknown force that causes life, that idea has been proposed historically, and shown to be unnecessary. The forces acting on inanimate objects are sufficient to explain life. That was the real point of the original experiments that synthesized organic compounds from inorganic precursors. Not that these experiments would realistically portray how life originally formed, but rather to render the notion of a "vital force" necessary for life unnecessary.