[EvaH (OP)]

Gordon asks:

As biology enters an engineering phase, when will we be able to model fetal development from conception to term, or beyond, with high-speed computer simulations of biological development at the cellular, structural, and phenotype level? What is required to get there? All other engineering technologies rely on modelling before building, and biology, ethics aside, seems to be on the same trajectory.

What do you think?

[alancalverd]

All other engineering technologies rely on modelling before building

Every living thing has been building before modelling, since life began - life is not engineering. And come to think of it. modelling is a relatively recent innovation in engineering. Looking around this office, a lot of stuff was drawn and shaped by computers, but probably only the airflow in he computers was modelled before drawing.

We know a great deal about the fetal development of most species that are of importance to us. Not sure what the value of a model might be. 

[evan_au]

I think that modeling biological systems is important - we see it at the moment with the rush to develop a vaccine against SARS-CoV-2.
- I think biological modeling is important for humans too, so that we can predict the behavior of medicines in the human body, and minimize side-effects. For this, we just need a snapshot of the human body at one point in time, not a complete development from fetus to adult.
- The ability to model from fetus to adult (and into senescence) would also be useful, to determine the causes and mechanisms of heart disease, Alzheimers, aging, etc. This would help with development of medicines.

Our abilities at the moment extend only far enough to allow some researchers to work out the structure of the SARS-CoV-2 spike protein, given its RNA sequence. They need to do this modeling to find likely targets on the outside of the spike protein that could be used as an antigen, and to produce neutralizing antibodies (to stop the virus entering a cell).
- Identifying the structure of a protein involves a multi-dimensional optimization using quantum effects, and takes a lot of computer time.
- Perhaps when we have quantum computers with a million or more qubits we will be able to model single proteins  routinely, but at present, Google claims it has the record for the biggest quantum computer, at about 48 qubits.

The human genome has about 20,000 to 25,000 protein-coding genes.
- There are a fair number of these for which we do not know the function
- These genes combine in complex ways to produce perhaps 100,000 proteins. Modeling all of these proteins is about 100,000 times beyond our current capabilities.

Another comparison: SARS-CoV-2 has about 30,000 bases in 1 strand of RNA.
- The human genome has about 3 billion base pairs of DNA x 2 copies of each chromosome.
- This is about 100,000 times more complex (x2, since we have two copies of each chromosome)
- A lot of the human genome consists of regulatory regions which interact in complex ways with epigenetic markers that we are only starting to map

So modeling the development of a human is far beyond our current capabilities.
- Well before that happens, we will be able to model the development of C.Elegans, a worm just about 1mm long, with only 300 neurons, and 1000 cells overall
- Long before that happens, scientists will be able to model the life cycle of the single-celled bacterium E.Coli
- So you will have plenty of warning before the development of a human is modeled!

See: https://en.wikipedia.org/wiki/List_of_model_organisms