This is a good question, because it highlights the idea that science and philosophy are not two crisp classes with no overlap in activity. Every science has a body of philosophy in it (and in fact, the philosophy of science is the starting point for each other philosophy, including the philosophy of biology, and it's a fine turn of the words that puts a question squarely in one category or the other.
So, your question is very specific. How do you formulate the question as a philosophical question as opposed to a scientific one is difficult since what is the nature of science (demarcation problem) is itself provisional on an argument by argument basis. This entire tangle really is a question of metaphysics, which Borchert's entry 'metaphysics' paraphrases to an exercise in developing an ontology, or a set of concepts from which one reasons. Obviously, this since the philosophy of biology uses both a philosophical ontology and a biological one, any question in the philosophy of biology will be allowed to use both, and illuminates the importance of using logics amenable to fuzzy membership.
The question of whether or not an organism is a member of Homo sapiens is a technical one, which would rely on the biological sciences to separate (presumably closely related) hominids like Homo neanderthalensis or Pan troglodytes from our species. This would rely on genetic testing, analysis of anatomical structures, and other topics that are biology per se. If you are just trying to find out how a police office who recovered genetic material wanted to verify it was human, then you would have to ask a geneticist who would be able to answer that question scientifically given knowledge of human genetics and it's diversity.
The question of how does one decide where to draw the line between Homo sapiens and Homo habilis is more a question of how does one decide how speciation occurs and what does it mean to be of two distinct species. Philosophers ignorant of science (and there are many of those) might presume that because it's related to biology, it should just be covered by biology and would have a grave misreading of the importance of philosophical argumentation determining the definition of species, which itself is not uncontroversial. Only an idiot who professes to be a philosopher could look at the demarcation of species problem and not see philosophy.
From the opening of the WP articles on the problem:
The species problem is the set of questions that arises when biologists attempt to define what a species is. Such a definition is called a species concept; there are at least 26 recognized species concepts.1 A species concept that works well for sexually reproducing organisms such as birds is useless for species that reproduce asexually, such as bacteria. The scientific study of the species problem has been called microtaxonomy.2
One common, but sometimes difficult, question is how best to decide which species an organism belongs to, because reproductively isolated groups may not be readily recognizable, and cryptic species may be present. There is a continuum from reproductive isolation with no interbreeding, to panmixis, unlimited interbreeding. Populations can move forward or backwards along this continuum, at any point meeting the criteria for one or another species concept, and failing others.
Many of the debates on species touch on philosophical issues, such as nominalism and realism, and on issues of language and cognition.
So, how do you tag/phrase your question to be philosophical? I would start by reading the aforelinked WP articles on the philosophy of biology and the demarcation problem of species and proceed from there. Reading those two articles will do a lot to get you to a question in the philosophy of biology, and away from questions like 'what is humanity' which, to those with scientific bent, seems like more like detached metaphysical speculation.