Does the asker of this question mean bi instead of phi? There are advantages to being a bi-ped organism. Two appendages allow equal forces to be applied to another object at the same moment. Our numerous fingers provide us with even a greater level of object manipulation. Having two arms allows us to pick up and move larger objects than our more closely positioned fingers would allow. There are obvious other advantages but, I'm being brief here.

The only "phi ratios" which are of specific interest in biology are the phi-pi ratios which are used to describe the angles of linkages between monomers of polypeptides, since the angles so described depend on the specific chemical properties of the monomers and will thus tell you what the amino acids involved are. However, I get the impression that this is not what you are asking... If you mean something like [ http://www.championtrees.org/yarrow/phi/phi1.htm ], then the biological principle of interest is "symmetry". And yes, there are biological advantages to symmetry. Symmetry is easier to "code for" genetically than asymmetry, in many cases; it is energetically efficient; and it is (in many multicellular animals, at least) an indicator of some degree of health, since perturbations of embryonic development due to maternal disease or malnutrition often result in asymmetries.

There is no proof that having Phi ratios throughout the body is anything more than just coincidence. Phi ratios refer to the ratio of sides in a "perfect", or "golden" rectangle: 1 to 1.61803399 (roughly). This ratio is seen throughout nature, in various forms (there are many websites that give examples of this phenomenon). This ratio is also seen many times in the human body. For example, the ratio is seen in comparisons of finger bone lengths, arm to forearm lengths, and a multitude of other body parts. The problem is that the ratios found in these body parts are not always EXACTLY Phi, but very close. If you choose a different ratio, say 1.9:1, you could find a large selection of body parts that fit this other ratio instead. So, the golden ratio Phi is DEFINITELY found in the human body, and throughout nature. But, finding it throughout the human body may just be coincidence, and not have any biological benefits or advantages. There are instances where it shows up in nature that are definitely advantageous, mostly having to do with efficient packing (in sunflower seed arrangements, or how leaves are arranged on a branch, for example.)

We can solve this quadratic equation to find two possible values for Phi as follows: First note that (Phi – 1/2)2 = Phi2 – Phi + 1/4 Using this we can write Phi2 – Phi – 1 as (Phi – 1/2)2 – 5/4 and since Phi2 – Phi – 1 = 0 then (Phi – 1/2)2 must equal 5/4 Taking square-roots gives (Phi – 1/2) = +(5/4) or –(5/4). so Phi = 1/2 + (5/4) or 1/2 – (5/4). We can simplify this by noting that (5/4) = 5/4 = 5/2 The two values are : 1/2 + 5/2 and 1/2 – 5/2 or 1·6180339887... and –0·6180339887... therefore the advantages are bigger body parts ie penis, breasts

you obviously dont know the advantages of a big penis im sorry if you do not have the capacity to understand my answer