ENV has an interesting article on the large pile of rocks found in the Sea of Galilee. Based only on their inability to think of a plausible natural explanation for the rocks, and that it resembles other known cairns, the researchers have inferred that the rock formation was made by humans. ENV suggests that if scientists are willing to infer design on such apparently weak evidence, then...
...how much stronger is the design inference when looking at the genetic code, with its elaborate translation, transcription, proofreading and duplication mechanisms? If these archaeologists can find design in a pile of rocks, why should biologists not find design in structures that clearly have specified complexity arranged for purposeful function?
I'm inclined to agree with ENV's argument, though with some reservation. If the archaeologists decide that the pile of rocks dates to millions of years before there were human beings on Earth, would they still think it was designed? I suspect not. I suspect that they would search for some natural explanation to explain its origin: earthquakes, floods, meteors, etc. In other words, what makes the design inference attractive is that there is independent evidence for a designer. Absent that evidence, such an inference becomes much weaker.
With that said, given what seems to be stronger evidence for design: "...elaborate translation, transcription, proofreading and duplication mechanisms..." I think there is still good grounds for a design inference for biological features...or at least for a design hypothesis.