The look in your example is likely not pure black-and-white. It appears closer to a warm-toned monochrome or duotone image, where grayscale is printed or toned with a slight yellow/brown cast instead of neutral gray.

Based on the answers, the main factors are:

• Higher contrast: deepen shadows and brighten highlights to give the skin more shape and separation.
• Warm toning: shift the whites/grays slightly toward yellow, brown, or gray-warm tones for an older, richer look.
• Selective editing: faces may be adjusted differently from the rest of the image to keep skin looking smooth and luminous.
• Printing matters: duotone or multitone printing can give smoother tonal transitions than simple black-ink grayscale.

So for your own shots, start with a monochrome conversion, increase contrast carefully, then add a subtle warm tone rather than leaving it neutral black-and-white. If printing, a duotone/toned print can enhance the effect further.