Motivated by the question What are the theological implications/problems with theistic evolution?, consider that Jasher 4:18 seems to imply that there is something wrong with the mixing of animal species to create "chimeras". The creationists group species into "kinds" but the naturalistic evolutionary view would probably say that the whole thing is a spectrum and that nothing is special about a particular given phenotype other than its current adaptability to the current environment, i.e. everything is just in continuous flux. But if Jasher 4:18 is true, then there is something "divinely special" about certain fixed phenotypes that we see nowadays. The two philosophies are completely in opposition. The technology to create chimeras will surely exist in future. What should a Christian say about chimeras? The view of Jasher 4:18 seems incontrovertible.
- Theistic evolution allows that God used evolution as tool prior to the creation of Man, but that this part of his plan is now completed, and he will no longer allow one "kind" to evolve into another "kind". A new species? Sure. A new genus? Maybe, if it's really similar to a prior one. After all, the classification system is an invention of man and therefore imperfect. A new family or phylum? Probably not gonna happen, except maybe among bugs or microbes. Note that theistic evolution doesn't demand this interpretation, but it allows it.
- The book of Jasher isn't exactly canon to most Christians.