Jeremy Rifkin says that he is seeking the patents on such a "chimera" in order to focus people's minds on the question of whether a human embryo can be considered intellectual property.
Mr Rifkin, who heads the business pressure group Foundation in Economic Trends, based in Washington DC, has applied jointly in the US for the patents with Stuart Newman, a New York scientist.
The creation of such a creature would be illegal in the UK under the 1990 Human Fertilisation and Embryology Act. But it would be legal in the US.
Neither applicant has actually produced such a chimera in the laboratory. Instead, they are exploiting a loophole in the US patent system which grants patents based on the description, rather than the demonstration, of a technique. The duo plan a similar application in Europe.
If the patents are granted, Mr Rifkin will hold them for "genetic conservancy" and refuse to license their use. He wants to spark a debate about the moral and ethical issues involved in patenting life and bioengineering humans. "There are serious constitutional issues involved here," he says. "Can a human embryo be considered intellectual property? This is the sort of question that we haven't debated in the US for 135 years - since slavery."
The problem, he says, is that the public does not really understand the consequences of the work currently going on in the biotechnology industry.
The creation of a human-animal chimera is the logical culmination of many projects being carried out by biotechnology companies. Already, it is common for transgenic bacteria and even animals to be given human genes. PPL, the company which helped produce Dolly the sheep, has a flock of sheep with a human gene to produce a protein for the treatment of cystic fibrosis.
PPL has applied for patents on cloning which its lawyers have confirmed would cover human cloning. And last year, Japanese scientists produced laboratory mice which had human chromosomes added.
A chimera would mingle the embryonic material of two species - which might have commercial applications. For example, a human-chimpanzee cross might be useful for testing new drugs to see if they would be harmful to humans or for examining human development.
But Thomas Murray, director of the Center for Biomedical Ethics at Case Western Reserve University, said: "If we put one human gene in an animal, or two or three, some people may get nervous but you're clearly not making a person yet. But when you talk about a hefty percentage of the cells being human ... this really is problematic. Then you have to ask these very hard questions about what it means to be human."Reuse content