You stink.
Sorry to be so brutally honest, but it's better that you hear it from me than by finding a
growing pile of soap or perfume left for you by work colleagues or family members.
Your natural aroma is the result of various things, including your diet and your genetic
make-up.
But the primary suspect is the apocrine sweat gland, present in both your arm pits and what
is delicately termed your genital region.
Each of your pits contains up to 50,000 of these glands, and the average human produces
around a litre of sweat everyday day.
But sweat itself doesn't smell strongly; it's basically just water and various salts.
Body odor is the result of billions of microorganisms that live on your skin, mostly bacteria.
The majority of these are not harming you and may even offer positive benefits, like
stimulating your skin's immune system.
But some of these, especially members of the Corynebacterium clan manufacture enzymes that
break down your honest, hard-working sweat into a variety of acids.
Many of which, including Propionic and Butyric acids, and especially trans-3-methyl Hexeomic
acid, stink.
Your armpits and - ahem - pubic region are also likely to contain thousands of thin,
wiry hairs - broadly similar to those that Jeremy Clarkson has on his head - and these
act to wick this pungent mixture, exposing more of it to the air to help it spread further
and faster.
And potentially enabling you to clear out a room by the simple act of walking into it.
Humans aren't alone in having a tendency to make strong smells, many animals have serious
B.O too.
And in the wild, it can be a huge advantage - marking out territory, attracting mates
or repel enemies.
Or even, in the case of creatures that feign death to avoid getting eaten, to persuade
potential predators that they are already rotting and not very palatable.
But for humans, smelling strongly is rarely regarded as a good thing.
And another problem is that our favoured way to clean ourselves, through the use of soap,
can actually intensify this natural aroma.
Naturally, our skin tends to be slightly acidic, but soap is alkaline and - using it repeatedly
encourages more alkaline-loving bacteria to flock to us.
Which is where deodorant comes in, killing or suppressing the bacteria through being
mildly acidic, and usually also carrying some perfume elements as well to make us smell
nicer.
It's not a new idea, naturally-occurring deodorising salts have been used for thousands of years.
But it took the marketing departments of big cosmetics companies, and the threat that your
'BO' was turning you into the office bogeyman, to see the idea really take off.
Because modern deodorants don't just make you smell fractionally fresher.
They also serve as anti-perspirants, reducing the amount you sweat.
The modern anti-perspirant was invented in the 1940s by a man with the spectacularly
French name of Jules Montenier.
Sadly, from the point of view of me now making a cheap gag about the French buying less deodorant
than any other developed country, Montenier was actually from Chicago.
So we can't do that.
Anti- perspirants contain an active ingredient to reduce the amount you sweat, and therefore
the amount of stink-fuel available to the bacteria on your skin.
This is almost always an aluminum compound ['aluminum' for our American viewers.
This will usually be aluminium chlorohydrade and aluminium zirconium trichlorohdrex, either
of which will react with the electrolytes in your sweat to create a thick gel that effectively
blocks the top of your sweat glands, and which also acts astringently to cause your pores
to contract.
Both of which reduce the amount you sweat, and therefore the amount you smell.
But is this a good thing?
There have been several health scares over the years about anti- perspirants, and they
were briefly banned in America in the 1970s over concerns about the long-term effects
of inhaling some of the aluminium compounds.
But more importantly, the anti- perspirants is also trying to prevent your body from doing
something it does naturally and for good reason, to help regulate your body temperature.
It's also treating an effect rather than a cause - research suggests that even extreme
body odor can be reduced through changes in diet and by doing more exercise.
But deodorants could also be preventing more than just a few sodden shirts.
There's evidence they can reduce the effect of your pheromones, the chemical markers that
we excrete and which help us to attract mates, or just casual sexual partners.
We're stinky for a reason.
Hai Karate or Old Spice never worked as well as good honest sweat.